Semiolog y of immune system. Department of pediatrics. No t i o n. Immune system reunites the organ s , tissues and cells , which ensure the defense of h uman organism against the genetically strange substances (antigen s ) by exogenous and endogenous origin . Immune system.
Department of pediatrics
reunites the organs, tissues andcells, which ensure the defense ofhuman organism against the geneticallystrange substances (antigens) by exogenous and endogenous origin.
Two possibilities of IS response manifesting were distinguished for to understand how the organism succeedsto put up resistance to the external medium factors (infectious agents) :
elimination ofpathogenic agents with the
nonspecific means of IS response or
producing of some cellular and molecular componentsfor adopting the pathogenic agent
The function of IS consists in the Ag identifying and generation of specific response –
accumulation of sensibilized lymphocytes, which will
eliminated the Ag from organism.
1. Lymphoid organs:
2. Humoral components
3. Cellular components
The central lymphoid organs (primary) are represented by:
The central lymphoid organs have a major significance inimmunitybecause they represent theplace oflymphopoiesis.
At their level, the cellular components of IS: B lymphocytes and T lymphocytes, aredifferentiatingfrom derived precursors originated from stem cell, proliferatingand se maturating in functional cells.
Hematogene marrow is localizing in the trabeculae of osseos spongious tissue fromlong bones epiphyses, from flat bones and from short bones. From the histologic point of view, it is formed from stroma, blood, lymphatic vesselsand nerves. The stroma is formed from conjunctive reticular cells, forminga network where are sitting the stem cells. Here the B lymphocytes are differentiating.
The thymus is sitting retrosternally.
From the anatomic point of view, the thymus is formed from two lobes connected by isthmus.
Each lobe is formed from lobules delimitedby conjunctive septa whichproceed fromthe capsula covering the entire organ.
Two zones are described in the thymic lobule: corticaland medullar.
The thymic cells are lymphocytes, epithelial and non-epithelial cells.
The process of differentiation is developing under the influence of local hormones (thymosine, thymopoietine, thymuline) secretedespecially by subcapsular and subtrabecular epithelium.
The thymus is forming at the end of first month of intrauterine development.
It is positioned retrosternally.
It is covered by conjunctive tissue capsulawhichseparates the organ in lobules.
Each lobulehas cortical and medullar layer. The cortical layer contains T-lymphocytes, and epithelial cells of medullar layer form the Gassale corpuscles.
The thymus releases in the systemic circulation
hormones (thymosine, thymopoietine, thymic factor etc.) whichregulates the proliferationand differentiation of lymphocytes.
The thymus achieves the maximal degree of development in early childhood.
In the period of 3 – 13-15 yrsthe stabilizationof gland mass has place, and ulterior it involutes.
The cortical layer becomesmore poor in T-lymphocytes, the Gassale corpuscles from medullar layer disappear, thesestructures beingreplacedwith conjunctiveand adipose tissue.
In rare cases the physiologic involutionis not producing.
These clinical situationsusuallyare associatedwithdiminishing of GCS secretionby cortical layer of suprarenal glands. Such patientsare more receptiveto intercurrent infections, have increased risc forneoplastic processes appearance.
Peripheral (secondary) lymphoid organs are represented by:
Lymphoid tissue from mucosae
The spleen is situatedin the left superior part of abdomen.
It has exterior capsulafrom conjunctive tissuewhichsendsin parenchymaprolongationsforming trabeculae. Thesetogetherwith the reticular cells network form a support for agreat lot of cells.
Two types of tissue enterin the spleen structure : the tissue responsibleforgrown old blood cells destruction and urgent generation of new erythrocytes, plateletsand granulocytes (red pulp) and tissue populatedbyimmune competent cells (white pulp).
Spleen white pulp is a lymphoid tissue situatedin two zones:
T-dependent zone, situatedaround central arteriolaand
B-dependent zone, whichsurroundsthe T-zone, as a muff.
In B-zone thecells are organizedinprimary follicles (non stimulated) and in secondary follicles (stimulated).
At the periphery of B-zone, to the exterior,the splenic macrophages are sitting.
The lymph nodes are oval
formations by different dimensions, situated in theconfluence placeofgreat lymph vessels.
The forming of LN begins in the 2-ndmonth of
intrauterine developmentand is finishing in thepostnatal period.
In new-born the LN capsula is very thin and
fine, the trabeculae are weakly differentiated, and
their palpationis difficult. LN are soft and they are includedin good developed adipose tissue at this age.
At 1 year age theLNcan be palpated at the majority ofchildren.
Parallel with their growing their differentiation has place.
In the 3 yrs age the capsula is good
At 7-8 yrstheforming of trabeculae in the
interior ofLN begins.
At 12-13 yrs the structure of LNisdefinitized, being good differentiated all theirstructures:
capsula, trabeculae, follicles, sinuses.
In the puberty period the LN growing
is finishing, and sometime evenpartially regresses.
The maximal number of LN is achieved
around10 years age.
The mature has approximatively
460 LN, having total mass by1%
from corporal mass (500 – 1000g).
Each lymph node (LN) is covered at surface with
conjunctive tissue capsule, and in interior contains
The lymphoid tissue of LN isseparated in two
Cortical layer isformedfromfollicles–
conglomeratesof B lymphocytes.
Inparacorticallayer the T-lymphocytes are placed
Inmedullarlayer the plasmocytes, secreting
immunoglobulins are placed.
LNareplaced in groups, throughthem the lymph
drainage from distinct anatomic zones has place.
Due to theirstructure and localization theLN
have a roleofbarrierin the pathway of infection
spreading, preventing its generalization.
LNfilter the particleswith antigenic properties,
and the lymphocytesand plasmocytesfrom
LN ensure the synthesis of antibodies.
The lymphoid system of respiratoryand digestive
tract ensures the good functioning of local
immunity at the level of their mucosa.
The reaction of LN at different stimuli, especially
infectiouscan be observed from 3 months age.
In 1-2 yrs age children thebarrier function of LN
is not good expressed, therefore in this age the
infections easily are generalized (septicemia,
meningitis, generalized forms of TBC).
Immaturity of lymphoid system at the level of
digestive tubepredisposes thesuckling babiesat
intestinal infectionsand allergization of organism on
In the antepreschool age theLNare still
good structuredand can serveas
mechanicalbarrier against the infection
In this age the lymphadenites, including
these purulent and caseous (TBC) are
In the age of 7-8 years the LNbecome
functional and can suppress the infection
through immunologic mechanisms.
Occipital– placedon occipital tuberozities – they collect the lymphfrom the scalp skinand cervical posterior region.
Mastoidian– placedin region of mastoid apophises, retroauricular – placed postrior fromears pavilion – both groups collect the lymphfrom medium ear, external auditive conduct, ears pavilion, paraauricular teguments.
Submandibular – placedunder inferior bundlesof mandiba – collect the lymphfrom face skin andgums mucosa.
Mentoniar– placedone self bilaterallyin the region ofchin – collect the lymphfrom the inferior lip skin, mucosa of gumsand from inferior incissives.
Anterior cervical and tonsilar – placed anterior from the sternocleidomastoidian muscle, in superior cervical triangle– collect the lymphfrom face teguments, from parathyroid gland, nasal, faringealand buccalmucosa.
Posterior cervical – placed posterior fromthe sternocleidomastoidian muscle, anterior fromtrapezium muscle, in cervical superior triangle – collect the lymphfrom cervical region and partiallyfrom larynx.
The LNfrom above mentioned groups are
frequently cataloguedas a unique group –
Supraclavicular– placedin supraclavicular fossa – collect the lymphfrom superior partofthorax, pleural domes and pulmonary apexes.
Subclavicular– placedin infraclavicular fossa – collect the lymphfrom the thoracic walland pleura.
Axillary – placed în axillary fossa – collect the lymphfrom superior members (exceptionfingers V, IV, III and palm).
Thoracic– placedon the inferior margin ofbig pectoral muscle – collect the lymphfrom thoracic wall teguments, parietalpleura, partiallyfrom lungs and mammal glands.
Cubital – placed in the cubital regionat the level of bicepstendon – collect the lymphfrom V, IV, III fingers and palm.
Inguinal – placedonline of inguinal ligament– collect the lymphfrom the teguments of inferior member, hypogastrium, buttocks, anal region, perineum, genital organs.
Popliteal– placedin the popliteal fossa – collect the lymphfrom the teguments ofleg.
The knowledge of LN localizationand of their draining zoneshas a major role in theidentifying ofinfectiongateway, especially in the case when the modificationsof infection gateway are minimal oreven absent, but regional LNwill reactin the all cases.
In the case of LN marked enlargement, the child or the
parents can remark this modificationand can present the respective complaints.
In the case of lymphadenitis thechild canaccusepain, tumefactionand hyperemiaat the level of affected LN.
Only LN which are placed superficially and are very enlarged in volume (lymphogranulomatosis, infectious mononucleosis) can be observed.
In lymphadenitisthe hyperemia of tegumentscovering theinvolved LN, which usually is tumefied and painful at palpation can be observed.
Palpation. At palpation the LNthe following
Characteristics are appreciated:
Dimension – usually theLNhave a diameter
around 0,3-0,5 cm (pea seed).
The dimension of LNisgradated as the following:
I degree – dimension of millet seed
II grad – dimension oflentil seed
III grad – dimension of pea seed
IV grad – dimension ofhorse bean
V grad – dimension of peanut
VI grad – dimension of pigeon egg.
Increasing of LN dimension poate can be isolated or in group, symmetrical or unilateral.
If in each group 3 or less LN are palpable – they are considered solitary,
If in some group more than 3 LNare palpated – they are considered multiple.
Can be soft, elastic, hard.
It depends from the oldness and nature of process:
in chronic pathology the LN are hard,
in the case of recent affectionthey have soft consistence.
Physiologically the consistence of LN is elastic.
Mobility – usually the LN are mobile.
Reportwith teguments, adipose subcutaneous tissue, other LN. Physiologically the LN don’tconnectwith adiacent tissuesand not between them.
LN are painless at palpation.
The presence of pain at palpation indicates an acute inflammatory process at the level of LN.
The palpation of symmetrical LN isperforming with both hands concomitantly.
(exception – cubital LN).
In healthy children until 3 groups of LN are palpable.
In physiological conditions the
The chin, supra- and subclavicular,
thoracal, cubital and poplitealLN
are not palpating.
The LN can be considered normal, if:
their dimension does notexceed the
dimension of pea seed,
by elastic consistence,
don’t adherebetween them and
are not painful.
For the performing of certain diagnosis, the clinical examination ofLN is supplementedat necessitywith special paraclinicalexaminations:
puncture of LN,
biopsy of LN,
In children the modifications of LN both local andgeneralized are frequently observed.
Local/regional enlargementof LN accompanies the suppurative processesat the level of teguments: folliculites, pioderma, furunculosis, miliary multipleabscesses , infected sores, hydroadenitis etc.
Lymphadenopathy – enlargement of LN in dimensions, sometimes with modification of their consistence.
Polyadenia – increasing of number of palpable LN.
In diphtheria, scarlet fever, tonsillitis the cervical LN react.
În felinosisthe cubital and/or axillary LN are modified.
TBC of peripheral LN usuallyislimiting at the affection of one group ofLN, most often cervical.
The LN represent a voluminous, hard, painless conglomerate (packet).
They are adherent between them and
They have tendency of evolution to the
caseous necrosis, with forming of
local fistula, after that the „ stellated scars” remain.
In theinfectious mononucleosis all groupsof peripheral LN are affected, but the affection of cervical posterior LN predominates.
In rujeolathe occipital LN are affected.
For rubeola the diffuse LN affection, more pronounced in cervical,
occipital and axillar LN groups is characteristic.
In adenoviral and paragrippal infection
the anterior and posterior cervical and occipital LN are predominantly involved.
In mumps the auricular LNare palpating as
firm formations which are placed
superiorly to parotidian tumefiated glands.
In toxoplasmosismost frequently
thegroups of cervical,
axillary, inguinal LN are affected. The LN have the dimensionsof a nut, sometimes can have a form of pockets, but each node can be palpated separately.
In HIV/AIDS thegeneralized lymphadenopathyis a precociousand constant symptom.
The diameter of LN is 2-3 cm, the contur net delimitated, hard atpalpation, not adhere between them and not to adjacent tissues, usuallyare sensibleat palpation, sometimes painful.
Lymphosarcoma ismanifesting by
affectionof isolated LN group,
usually cervical or supraclavicular.
LNare very hard, painlessatpalpation,
the local signs of inflammation are
The generalized lymphadenopathy can
be present in a lot of acute or chronic
infectious pathologies and in
The diffuse diseases of conjunctive tissue can be around the noninfectious causes of generalized lymphadenopathy.
Lymphogranulomatosisas a rule beginswith
peripheral LN affection, more frequently cervical or/and mandibular. In the same timewithdisease evolution the LN grow in conglomerates.
LN are painless, atpalpationcreates a sensation of „sackofpotatoes”. The diagnosis is confirmed by the hystologic examination of LN (Berezovski-Sternberg cells).
In ALL (acute lymphoblastic leukaemia) all
groups of LN are rapidly growing in
dimensions. They are soft and painless atpalpation.
The lymphoid tissues associated to mucosae also enter in the category of secondary lymphoid organs.
These can be:
good individualized anatomically structures
lympho-epithelial diffuse structures.
The individualized anatomically structures are:
1. Componentele of Valdayer lymphatic ring
a) lingual tonsils
b) palatine tonsils
c) tubar tonsils
d) faringean tonsils
2. Payer’s patches
3. Vermiform appendix
The diffuse lympho-epithelial tissues
Are localized at the level of digestive, respiratory, genito-urinary tracts etc.
After their localizationthese tissues were named:
MALT – mucosae associated lymphoid tissue
SALT – skin associated lymphoid tissue
BALT – bronchia associated lymphoid tissue
GALT – gut associated lymphoid tissue
The factors of nonspecific protectionhave a large spectrumof action, that is possessa high specificity.
Thenonspecificforces of protection are sufficient for to combat the majority of pathogen agents.
Nonspecific reactions are at the basis of natural immunity and offer to organism the immunityeven against the pathogen agents which the organismdidn’t anteriorly met.
These factors beingphylogeneticallyolder have a decisive role
In the protection of nevborns
until the maturation of specific immune mechanisms.
is ensured by the
physiologic barriers and
humoral nonspecific factors.
In the physiologic barriers enter:
tegumentsand intact mucosae,
acid gastric medium,
kidneys (which excretesome
microorganisms, especially viruses).
Nonspecific humoral protection isensured by:
properdin, present inbloodand other BL,
The last two componentshave special statusbeing mechanismsof nonspecific and specific protectionin the same time.
Lysozyme– a protein which possesses enzymatic qualities. It destroy the structure of mucopolysacharides of cellular bacterial membranes. It isvery active on Gramm “-” bacterias.
Secretory Ig A potentiates theaction oflysozyme. The most high level oflysozymeis in newborns, and further decreases gradually.
Properdin – a plasmaticglobulin, whichactivatesalternatively the complement and togetherensure theelimination ofviruses and bacterias from organism.
The contain de properdin in children is low, at the 1-3 weeks its level rapidly increases and remains high during all childhood.
Interferon – a protein with antiviral action, which is manifestingin the phase of de intracellular virus replication.
It can be synthesized by each cellofhumanorganism, but especially by leucocytes.
blocks themultiplication of chlamidias,
plasmodium malariae, ricketsies,
increases the organism cells resistanceto
the action of exo- and endo
increases the cytotoxicity of lymphocytes,
blocks the cangerogenesis,
Influences the antibodies forming
(small doses – stimulates it, and
high doses – inhibates it).
In newborns the capacityof interferon synthesisis low, increases gradually and achieves the maximum at the age of 12-16 years.
The complement (C) – enzymaticsystem, formed from plasmatic globulins, the biologic role of al which is the cellular antigens lysis (viruses, virus infected cells, bacterias, mycoplasmas, protozoa, tumoral cells) fixedby Ab.
It includes 11complement fractionsand 3 inhibitors.
All components of complement system circulatein blood under the form of precursorswhich can be activatedon 2 pathways:
The trigger of classic activation pathwayis the Ag-Ab complex.
In the absence of Ab the complement system can be activated through alternative pathway – properdinic.
Phagocytosis – a processof capture anddigestionof Ag by tissular macrophages (monocytes) and circulant macrophages (neutrophilsand monocytes). The phagocytesare the first cells whichenter in contact with exo- or endogenous Ag.
The immune protection isensuredby 2 specific mechanisms :
whichare differing from one another by the mechanismsof
The immune response is ensured by
T-lymphocytes (thymodependent) and
The both cellular lines have a common predecessor –stem cell, whichmigratesfrombone marrowin thymus and in analog of Fabricius burse, when the differentiation and theirmaturation have place.
Thenthese cells populate the T şi B zones of LN. Here, at the first meeting with Ag their sensibilizationand ulterior differentiationinanother 2 subpopulations have place:
effector cells and
Effector cells – participate directly in the „liquidation” of antigenic aggressor. In the cell immunity there are cytotoxic T-lymphocytes (T-killer). They neutralize the antigen directlyorthroughsome special biologic active substances – lymphokines.
The memory cells are the lymphocyteswhichare transforming in the inactive form, but preserve the information about the Ag. These cells are going in again in the sanguine and lymphatic circulation and „patrol” the organism.
The humoral immunity is ensured by
Initially theT-lymphocytes are stimulated,
And they will be transforming in T-helpers.
These through interleukinswill stimulating the transforming of B-lymphocytesin plasmocytes, which will synthesizethe specific antibodies.
So, the effector cells of humoral immunity are plasmocytes.
B-lymphocytesreceive also informationabout the nature of Ag and from macrophageswhichcaptivatethese antigensandremakethem primarly.
In this way for good functioning of IS anharmoniouscollaboration between these three types of immunocompetent cells is necessary:
T-, B-lymphocytesand macrophages.
In the same time during antigenic stimulation the T-suppressors are forming. Theyblock T-helperis, in this wayblocking the Ab synthesisby B-lymphocytes.
This capacity of the organism is the basis of immunotolerance.
There are the soluble molecules, synthesizedby a great varietyof cells, inclusively by lymphocytes, with the roleofhumoral messengers, which realize thecommunicationbetweendifferent cells, controlling theirgrowing, differentiation, maturation, division, metabolism, functions.
T- and B-lymphocytescan be foundfrom the age of 10-12 weeks of intrauterine development.
T-lymphocytesbecome functionally afterthe age of 14-15 weeks of intrauterine development.
The newbornshave a more number of
T- and B-lymphocytescomparatively with another age andadults, but these cells are notcompletelyfunctional.
B-lymphocytessynthesizemore classesof Ig: G, M, A, D, E.
In each antigenic aggressiona lot of Ig classes are synthesized
As a response to primary contactwith Ag the Ig M, after that IgG, ulterior IgA are synthesized.
At repeated contact with Ag the IgG from start is synthesized.
IgG constituies 70-80% from the totality of plasmatic Ig.
It is the self Ig which passes the placentar barrier, ensuringthe passive immunity of thenew-born.
Transmission of IgG from mother to fetus has place more actively in the last weeks of pregnancy, thus the level of IgG in premature babiesis less thanin term born baby.
During the time the level of maternal IgG in blood plasma of suckling babydecreases, and achieves the minimum at 6-9 months.
At the age of one year the intensity of proper IgG synthesis constitutes 50% from that of adult.
At 4-6 yearsthe level of IgG in children achievesthe IgG level at adult.
IgM constitutes 5-10% from total plasmatic Ig. They constitute the first lineof defensive taking partin the complement activationon classic pathway, agglutinationand opsonization of Ag, lysisofalien cells.
In plasma of newborns the level of IgM is low, but increases quickly, achievingthe adult level at the1-2 years age.
IgA constitute 10-15% from total plasmatic Ig.
They aresynthesizedby plasmocytes, whichare localizedat the level of mucosaand submucosa of digestivetube and respiratory pathways.
The most partof IgA remainsin the place of synthesis(secretory IgA), ensuring the local immunity.
Secretory IgA is finding in tears, saliva, nasal andbronchial secretions, secretions of digestive tube, colostrum.
The level of secretory IgA in children is low. It increases with age and achieves the most high level at 5 years.
Seric IgA in children is less active.
In usual newborn is absent. It appearsafter first week of life.
At 1 year age the IgA level constitutes 20% from that of adult, which is achieved onlyat 10-12 years age.
IgD and IgE are containing in în non significant quantities(each - 0,2%).
IgD is a globulin by embryonic type.
It is enable to activate the complement on alternative pathway, to neutralize someviruses.
IgE constitutesthe most part of reagines – antibodies responsibleby allergic reaction releasing.
They aresynthesizedasresponseto primary contact with Ag.
IgE are fixed on the mastocytes and basophils surface, realizingthereforethe state of sensibilization.
At the repeated contact with Ag the IgE provokesthe degranlationof these cellswith eliminationfrom them of different BAS, their biologic effect being at the basis ofpathological modifications in allergic reactions.
IgE is practicallyabsentin the plasma
During the time their concentrationincreasesachievingthe adult level at 10-12 years age.
Therefore,the IS development is an ontogenetic process genetically programmed. The forming process is initiating intrauterine.
The most important stimulusthe IS receives after birth, when the exo- and endogenous antigenic aggression, determinedespecially by digestive tube, superior respiratorypathwaysand tegumentsmicrobial population by conditioned-pathogene microflora,increases considerably.
Immaturity of IS in children makes them
More sensible to intercurrent infections,
favour the generalizationof infectious processwith the development of septicemiaand septicopiemia,
favour themore severe evolution of infectious pathologies.
Three types of this system functions affection are possible:
Defect of one link of IS
(primaryand secondary immunodefficiencies)
Autoaggressionagainstthe normal structuresofhuman organism
(auoimmune diseasesanddiseases due to immunocomplexes)
Dysfunctionswhen some functions of IS areexagerratedin the detriment of another (lymphoproliferative syndromes)
The states of immunodeficiency appear as a result of oneor more links of IS function abolition.
The states of immunodeficiency are:
primary (inborn) and
The states of primary immunodeficiencyaredetermined by:
primaryaffection of T-lymphocytes;
primary affectionof B-lymphocytes;
combined affection of T- and B-
the summary incidence of primary
immunodeficiencystatesis by 2:1000,
50-70% beingprimary defects of
B-lymphocytar system, and
5-10% of T-lymphocytar system.
The child supports frequentlyinfectious
recurrent diseasesespecially of respiratory
pathways, digestive tube, reno-urinary
system, teguments, frequently complicated
with otitis, purulent sinusitis and septicemia.
They manifest unusualreactionsat banal
infections (ex. pneumoniaat varicella).
The sufferingis determined by unusual
causal agents (ex. Pneumocystus Carinii)
Presenceof some systemic reactions
after vaccination with live viral
attenuated vaccines or BCG
Bizarre hematologic deficit
Disorder of digestion with the development of malabsorption syndrome.
Secondary immunodeficiencies are determined by a lot of pathological states which lead to the involution of lymphoid tissue,lymphopenia,hipogammaglobulinemia.
They are the following:
pathologic states associatedwithlossof proteins:
nephrotic syndrome, combustions, exsudative enteropathy
Viral(flu), bacterial (holera),
micotic (candidosis) infections, helminthiases
Massive surgical interventions and/or
postoperatoryyatrogeniccomplications (irradiation, imunosuppressives: GCS,CS)
In childrenfirst 3 yrs of lifethe state of immunodeficiencycan be determined by
thymomegaly, which is induced by hypothalamo–hypophysar-suprarenalaxe affection.
In stress situations an rapid accidental involutionof thymus can be developing, inwhich a massivereleasing of T-lymphocytesin blood has place, their massive death inthymus with their phagocytosis by macrophages has place .
Transitory deficit of humoral immunityis characteristic forfirst year age children,
between 6 – 9 months.
Primary affection ofnonspecific factorsof protection includes
disorders in Complement System
disorder of phagocytosis.
The genetic deficit can involve each component of Complement System, which shell alter their cascade activation.
It is clinically manifesting throughdecreased resistance at bacterial infections (C1, C2, C3, C5), increasedincidence of hipersensibilitydiseases (C1, C2, C4). Deficit of C1leads to developmentof angioneurotic recurrent edema.
Patients with disorderedphagocytosis support frequent infections causedby microorganismsusuallynon pathogene.
In chronic granulomatosis (syndrome of paradoxes) the patients are resistant toinfectionswith high virulence microorganiss (streptococci, meningococci, pneumococci), but are sensibletoconditioned pathogene microorganisms (Escherihia coli, staphylococci).
A global affection of all components ofImmune System
And of humoral nonspecific iactors
Is characteristic for
Tere are a periods, when the organism immunesystem in growing and development
Generates paradoxal orunadequate responsesto antigenic stimuli.
I-st critical period – first month of life.
II-ndcritical period – from 3 to 6 month of life.
III-rdcritical period – second year of life.
IV-thcritical period – from 4 to 6 yrs of life.
V-thcritical period – period of adolescence.
First critical period–
first month of life.
A decreased activity of phagocytes
Lymphocytesare capable toreact
at antigenic stimuli and mitogenic
Humoral immunity is ensured by
The second critical period–
from 3 to 6 months of life.
Maternal antibodies disappear fromchild’s plasma,
the proper IgM is synthesizing as a response to antigenic stimuli.
Deficit of IgA predisposesto frequent
infectionsof respiratory pathways (viral).
Immunocompetent cellshave a diminished activity.
In this period the primary immunodeficiences are manifesting.
The third critical period–
the second year of life.
Immune system is completely functional.
The capacityof IgG synthesis increases,
but the mechanisms of local protection
remain insufficient developed.
Thismaintainsa high receptivity of the
child’s organism to different
The fourth critical period–
from 4 to 6 years of life.
The antibodies synthesis, excepting IgA,
achieves the level of adult.
Concomitantlythe titre of IgE increases.
The activityof local protection factors
In this age the tardive congenital immune defficiencies are clinically manifesting.
The fifth critical period–
the period of adolescence.
The gonadian hormones secreted in this
period inhibate the immune reactions.
As a result the autoimmune andlymphoproliferativepathologies can develop.
The increased receptivity
to diverse micobial agents is observing.