IMMUNITY - PowerPoint PPT Presentation

IMMUNITY

HMIM BLOCK 224

Dr. ShaikhMujeeb Ahmed

Assistant Professor

AlMaarefa College

• General overview of the immune system
• Different components of innate & acquired immunity.
• Phases of immune response.

Immunity is the body’s ability to resist or eliminate potentially harmful foreign materials or abnormal cells.

• Innate (natural) immunity
• Acquired (adaptive) immunity

• Nonspecific responses
• Inherent (innate or built-in) defense mechanisms
• Nonselective defend against foreign or abnormal material of any type, even on initial exposure to it.

• Barriers
• Physical
• Chemical
• Defensive cells
• WBCs
• Macrophages
• Natural killer cells (NK)
• Chemical defenses
• Complement system

• Integumentary system
• Mucus membrane & lysozyme

• Langerhans cells
• Phagocytes
• Natural killer cells
• Basophils and mast cells

• Interferon: (are named after their ability to "interfere" with viral replication)
• Complement system: (helps or “complements” the ability of antibodies and phagocytic cells to clear pathogens from an organism)
• Inflammation: (biological response of vascular tissues to harmful stimuli)

• α, β, and γ interferon
• By infected cells
• Function by blocking viral reproduction

Mechanism of Action of Interferon in Preventing Viral Replication

Complement System

Series of ~ 20 proteins

Activated by microorganisms

Will coat the microorganisms

Adherence reactions

phagocytic cells have receptors for C3

Biological active fragments

produce reactive oxygen intermediates

Membrane lesions

Activate mast cells

• specific immune responses selectively targeted against a particular foreign material to which the body has already been exposed.
• The foreign material may be an antigen or a hapten (is a small molecule that can produce an immune response only when attached to a large carrier such as a protein)

• Antigen – “any substance when introduced into the body stimulates the production of an antibody”
• Bacteria, fungus, parasite
• Viral particles
• Other foreign material
• Pathogen – an Antigen which causes disease

• Antibody– “a Y-shaped protein, found on the surface of B-Cells or free in the blood, that neutralize antigen by binding specifically to it”
• Also known as an Immunoglobulin

Antigen

• Not antigenic by itself
• When combines with protein it become an antigen

• Two types
• Active immunity – direct encounter with the antigen.
• Passive immunity – without encounter with the antigen
• Antibodies transferred from mother to the fetus.
• Immunization by injecting antibodies

• Cell mediated immunity (T cell immunity)
• Antibody mediated (humoral/ B cell) immunity

After early childhood most new lymphocytes are derived from peripheral lymphocyte colonies rather than from bone marrow

Interactions between T- and B-Cells

T- memory Cell

T-supressor

Pre-T

Cell

T8-ctotoxic

T-Cell

T4-helper

Bone Marrow

Pre-B

Cell

Plasma Cell

B-Cell

B- memory Cell

IgG

IgA

IgD

IgM

IgE

• Initial phase
• Entry of antigen and its contact with the specific receptor on lymphocytic membrane.
• Central phase
• Cooperation among different subset of lymphocytes that proliferate and differentiate to form T & B lymphocyte + memory cells
• Effector phase
• Inactivation of antigen by sensitized T & B lymphocytes

• Human physiology by Lauralee Sherwood, seventh edition
• Text book physiology by Guyton &Hall,11th edition
• Text book of physiology by Linda .s contanzo, third edition