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Sri Ram .P Date: 11/25/03 Course: Scientific Discovery Instructor: Dr. A. Vankley. Cell Mediated Immunity. “Discoveries concerning the specificities of Cell Mediated Immune defenses and their implications ”. Immunity?. Foreign Invaders. Self Markers. Markers of Non-Self.

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Sri Ram .P Date: 11/25/03 Course: Scientific Discovery Instructor: Dr. A. Vankley

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Sri Ram .PDate: 11/25/03Course: Scientific Discovery

Instructor: Dr. A. Vankley

Cell Mediated Immunity

“Discoveries concerning the specificities of Cell Mediated Immune defenses and their implications ”


Foreign Invaders

Self Markers

Markers of Non-Self

Organs and tissues of the immune system

  • Lymphatic vessels form a circulatory system that operates in close partnership with blood circulation.

Lymph Node

Cells of the Immune System

  • B cells become plasma cells, which produce antibodies when a foreign antigen triggers the immune response.


  • Antibodies produced by cells of the immune system recognize foreign antigens and mark them for destruction.

  • Activation of B cells to make antibody

  • T lymphocytes become CD4+ or helper T cells, or they can become CD8+ cells, which in turn can become killer T cells, also called cytotoxic T cells.

  • Activation of helper T cells

  • Activation of cytotoxic T cells

Cytokines Complement

Natural Killer cells , Phagocytes and Granulocytes


Immunity and Cancer

Human Tissue Typing for Organ Transplants

Rolf M. Zinkernagel

Rolf M. Zinkernagel

  • Born: January 6, 1944, Basel, Switzerland

  • Primary and Secondary Education in and around Basel.

  • 1962-68:University of Basel, Faculty of Medicine

  • 1969- Began his life as Surgeon in Basel but soon realized this was not his field.

  • 1969-70:Postdoctoral Fellow, Laboratory for Electron Microscopy, Institute of Anatomy, University of Basel

Rolf M. Zinkernagel

  • 1971-1973 Postdoctoral Fellow, Institute of Biochemistry, University of Lausanne, Switzerland

  • He learnt his immunology here.

  • He also familiarized himself with the 51-Cr. Release assay to study the immune mechanism destruction of host cells.

  • His work with infectious agents and immunity studies motivated him for further study .

Rolf M. Zinkernagel

  • 1973-75:Visiting Fellow, Department of Microbiology, The John Curtin School of Medical Research, Australian National University, Canberra, Australia

  • 1976-79:Associate (Assistant Professor), Department of Immunopathology, Research Institute of Scripps Clinic, La Jolla, California

Rolf M. Zinkernagel

  • 1979-88:Associate Professor, Department of Pathology, University of Zurich, University Hospital, Zurich

  • 1988-92-Full professor in same place

  • 1992-Head, Institute of Experimental Immunology, Zurich

Peter C. Doherty

Peter C. Doherty

  • Born: October 15, 1940, Australia

  • 1962:BVSc University of Queensland, Australia

  • 1966:MVSc University of Queensland, Australia

  • 1967-71:Scientific Officer, Senior Scientific Officer, Department of Experimental Pathology,Moredun Research Institute, Edinburgh, Scotland

Peter C. Doherty

  • 1972-75:Research Fellow, Department of Microbiology, The John Curtin Schoolof Medical Research, Australian National University, Canberra, Australia

  • 1975-82: Associate Professor/Professor, The Wistar Institute, Philadelphia, PA

  • 1982-88:Professor and Head, Department of Experimental Pathology, The John CurtinSchool of Medical Research, Australian National University, Canberra

Peter C. Doherty

  • 1988:Chairman, Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN

  • 1992:Adjunct Professor, Departments of Pathology and Pediatrics, University of Tennessee, College of Medicine, Memphis, TN  

Paired Up

  • Peter Doherty first studied the pathogenesis of Semliki Forest virus infection in the mouse, then switched to the lymphocytic choriomeningitis virus (LCMV) model which was a much more powerful tool for immunological analysis.

Paired Up

  • Zinkernagel wanted to work with R. Blanden on cell-mediated immunity against Salmonella and Listeria to learn more about the role of cell-mediated versus antibody-dependent immune effector mechanisms in these infectious disease models . But lack of space in the lab paired both of them.


In 1960-70s immunology was attempted to be understood in terms of infectious diseases. It was then Largely pre-occupied with antibody and T-cell responses against foreign protein antigens or chemically defined small molecules called haptens.


  • Mechanism of foreign-organ graft rejection was intensively studied, although the biological function of MHC was largely unclear.

  • Only few people studied immunity against infectious agents.


  • Antibacterial and antiviral T-cell mediated immunity and the capacity of immunized cytotoxic CD8+ T cells to destroy either virus infected or allogeneic target cells in vitro- was the work in progress at JCSMR.

Techniques and Study

  • Doherty and Zinkernagel jointly begin work on CMI in LCMV (Lymphocytic choriomeningitis virus).

  • 51 cr. Release assays as cytotoxicity assay was used by Zinkernagel.

  • Doherty was efficient in cannulation and could draw few ml of CSF from cisterna magna of the mice.

Techniques and Study

  • Whether inflammatory cells in the CSF of mice infected intra cerebrally with LCMV were cytolytic in vitro and whether there was any correlation between cytotoxic T- cell activity and severity of choriomeningitis .


  • Cytotoxic T cells specifically destroying LCMV infected target cells could be found in CSF of normal mice but not in nude mice lacking thymus and T-cells.

  • T-cells probably also destroyed infected meningeal and ependymal cells in vivo and this was the pathogenic mechanism causing choriomeningitis.


  • The findings were published in the Journal of Experimental Medicine in March 1973.

  • Same journal had a paper showing mice with different major histocompatibility gene complexes differed in susceptibility to LCMV after cerebral infection.

  • This prompted to experiment further on this.


  • 6-8 mice of inbred and cross-bred strains were infected intra cerebrally with LCMV.

  • 2 of each were sacrificed on day 7 after infection when first mouse became sick. –to test antiviral cytotoxic T –cell activities in spleens.

  • Remaining mice were monitored for lethal disease during next 10days .


  • All mice died in course of time.

  • But only some generated virus-specific cytotoxic activity that was measurable in vitro.

  • Result- Either cytotoxic T-cells have nothing to do with choriomeningitis or the test was inadequate.


  • Mouse L-929 cells (fibroblast cell lines) were used as target cells to assess cytotoxic T-cell activity.

  • Fortunately the mouse CBA strain and the L-cells derived from mouse strain C3H were closely related.

  • Both possessed the same MHC-molecules (H-2k).


  • Studying further, LCMV -immune spleen cells from all mice that possessed H-2k haplotype (as do CBA mice) including the cross breeds with H-2k lysed L-929 cells infected with virus.

  • But did not lyse uninfected targets or those infected with third-party virus.

  • All spleen cells derived from immunized mice that were not of H-2k type failed to do so.

Further Studies

  • Two additional experiments showed that LCMV immune lymphocytes from non-H2k strains of mice were able to lyse LCMV infected target cells of same MHC –type.

  • LCMV did not infect these cell lines.

  • Used macrophages from the peritoneum of the mice as target cells. Adhered to plastic, readily infectable and labeled with Cr 51.

Further Studies

  • Criss-cross experiments showed that LCMV immune T-cells from H-2b mice lyse LCMV-infected macrophages of H-2b origin but not those of other H-2 types and vice versa.

  • These findings were reported in December to Nature and were published in April,1974

Similar Finding

  • TNP-specific cytotoxic T cells lysed syngeneic TNP-lated targets more efficiently than allogeneic TNP-lated targets.

  • European journal of immunology –same time . But independent.

How to Interpret

  • Biological function of MHC and TA was unknown in early 1970s.

  • TA-Gorer and Snell

  • HLA-Dausset and Van Rood

  • Many patients were typed and disease susceptibilities were linked to TA

  • Mice MHC was mapped due to availability of well-bred strains.

How to interpret

  • MHC polymorphism- to prevent mutual parasitism or transmission of tumor cells or to prevent viruses or pathogens mimicking TA and eliminate the species.

  • TA were though to act as enzymes or generators of antibody diversity.

The best proposal

  • H.S Lawrence proposed infectious agents complexed with TA and formed a (self+x) complex.

  • All this was foundation to reveal the essential role of MHC and T-cell recognition.

Crucial findings

  • Finding of double specifity by Tcells– for virus and MHC from intial experiements.

  • Findings that H-2 incompatible T-helper cells transfused to T-cell deficient nude mice were not able to help mice nude B cells make antibodies

  • Histo-incompatible B cells and T cells were not interacting successfully to produce a good IgM to IgG switch.

Crucial findings and Analysis

  • Antigen specifc proliferative T-cell responses found only when primed T cells and antigen presenting cells were with same MHC type.

  • All in vitro and in vivo tests confirmed the HLA restriction for T cells.

  • Virus infection somehow caused alterations of TA on the cell surface by forming a complex of viral antigen with MHC molecules .

  • These alterations were recognized by the T-cell receptors

Intimacy Model

  • Foreign TA altered forms of self-TA

  • Lymphocytes and target cells interact mutually via TA. H-2k interacts best with H-2k in a symmetrical like-like complementarity.

  • This initmacy model was soon excluded by the F1-experiment showing virus specific cytotoxic T lymphocytes from heterozygote F1 mice consisted of at least 2 subpopulations-each being specific for infected H-2k and other for H-2b targets.

Codominant Expression

  • Since MHC expressed codominantly some T-cell receptors of one population were probably specific for H-2k plus virus and other sub-population was specific for H-2b plus virus.

  • Working with Blanden’s experiments showed that H-2d and H-2k regions coding for class1MHC molecule were involved in virus-specific cytotoxic t-cell recognition.

  • This seperated MHC restricted recognition by virus-specific cytotoxic T-cells from MHC class 2


  • In 2nd letter to the Nature -T-cells might function to survey the integrity of TA. Recognition of cell surface alteration due to virus infection ,chemical modification or genetic differences may be accommodated in the same model.

  • General hypothesis formulated in Lancet was that function of MHC is to signal modifications of self-MHC to the immune system.


  • Tried to extend the explanations to helper T cells-they might recognize antigen-induced modifications of 1a(as the MHC class 2 molecules) on B cells and macrophages.

  • Explained the extensive polymorphisms of MHC molecules minimizing failure of some pathogens to cause immuno-modification and risk general unresponsiveness.

Role of Peptides

  • Not know then , MHC molecules are recognized as complex with antigenic peptide.

  • By works of Unanue, Grey and others on class 2 antigens and Townsted works showed- class 1 molecules of the virus infected cells present peptides ,9-10 amino acids long to virus specific cytotoxic t cells. These peptides were later successfully eluted

Role of Peptides

  • In 1987 x-ray crystallography revealed a peptide binding cleft.

  • X-ray structure of the complete complex of the T cell receptor-MHC class1 plus the bound peptide in same year of Nobel prize.

  • Still unclear which part of the TCR and whether always corresponding parts of the TCR recognized the peptide and the MHC molecule in the same general position.


  • The above findings and conclusions gave immense scope for further understanding of the immune system and its clinical implications in the field of medicine.

Role of Thymus

  • Reconstitution of lethally radiated H-2b recipient mice with bone-marrow stem cells of (H-2k*H-2b)F-1 origin resulted in bone marrow chimeras tolerant to H-2k and H-2b .

  • When immunized these reacted against only H-2b+minor HC antigens or H-2b+virus only.

  • So, MHC restricted T cells were specifically selected during T cell maturation according to the MHC expressed in the thymus.

Role of Thymus

  • MHC specificity studied in mice that lacked thymus did not have mature t-cells.

  • Introducing H-2k thymus into F-1 mice gave T–cells recognizing virus infected H-2k but not infected H-2b target cells.

  • Clinical implications – It is not only necessary to deplete T cells to avoid lethal graft versus host disease.

  • But also, host, transplanted bone marrow and hosts own or transplanted thymus grafts must share MHC molecules.

  • Other wise no proper immune reaction can be mounted in such reconstituted hosts.

New Vaccines

As peptides from viruses, bacteria and parasites are presented to the MHC class 1 or 2 molecules it was suggested that instead of live potentially harmful peptides could possibly be used as vaccines to induce T- cell responses.

New vaccines

  • Peptide life was short lived therefore adjuvants are required to guarantee slow and long term release of the peptides triggering T cells over a prolonged period.


  • Positive vaccination- increase the T cell precursor frequency to enhance protection.

  • Negative vaccination- to reduce or delete Tcells by excess peptide . To exhaust or delete immuno patholgical disease causing T-cells. Tried in diabetes.

Mutant viruses

  • T cell epitope escapes mutant viruses-

  • Mutation of the 9-10 a.a peptides such that its presentation by MHC molecules or recognition by t-cells is no longer possible. this helps viruses escape immune surveillance

Mutant Viruses

  • Infected mice in the footpad gave 2 peaks of immune reactions.

  • Similar mutant virus are seen in HIV and HBV infections.

MHC Associations

  • Linkage between some disease susceptibilities and certain HLA-types – important role of MHC molecules in immunity.

  • These autoimmune or immunopathological diseases are linked often to HLA class1 rather than class 2 molecules.

MHC Associations

  • As antigenicity and immunogenicity are linked to MHC and correlate with different strengths of the T cell response, shows that different MHC molecules directly determine and regulate resistance to diseases.

HLA associated diseases-Ankylosing Spondylitis

Autoimmune Diseases

  • Non cytopathologial viruses are not directly responsible for disease by themselves ,instead by the damaging effect of the protective T –cell responses.

  • Differences in MHC may influence the severity of the disease depending on the immunopathological response of T-cells.

  • These are the basis for autoimmune or immunopathological diseases.

Autoimmune Diseases

  • Multiple sclerosis

  • Diabetes mellitus

  • Rheumatoid Arthritis

  • SLE

  • Psoriasis

  • Hashimotos thyroiditis,etc

Autoimmune Diseases

Immunological memory

  • The concept of immunological memory has been exploited in vaccinations.

  • The B and T cells were found to exist as memory cells and hence maintained certain precursor levels to fight infections better.

  • The use of immune memory were explained for the mother and fetus.

Other Related Diseases

  • 1- Immune complex diseases. Ex. Glomerulonephritis

  • 2-Immune Deficiency diseases. Ex. AIDS

Team Work

Thus the combined efforts of doctors, immunologists, geneticists, virologists, microbiologists, etc helped us reveal the recognition of viral infected cells by T cells.

Giving insight into immunological specificity and memory and help understand immunological disease pathogenesis.

  • In recognition of these contributions Peter Doherty and Rolf Zinkernagel were awarded the Nobel Peace Prize in Medicine in year 1996.


1. Zinkernagel RM, Doherty PC. Restriction of in vitro T cell-mediated cytotoxicity in lymphocytic choriomeningitis within a syngenic and semiallogeneic system. Nature 248, 701- 702, 1974. 2. Zinkernagel RM, Doherty PC. Immunological surveillance against altered self components by sensitised T lymphocytes in lymphocytic choriomeningitis. Nature 251, 547-548, 1974. 3. Doherty PC, Zinkernagel RM. A biological role for the major histocompatibility antigens. Lancet, 1406-1409, 1975. 4. Zinkernagel RM, Doherty PC. MHC restricted cytotoxic T cells: Studies on the biological role of polymorphic major transplantation antigens determining T cell restriction specificity. Advances in Immunology 27, 51-177, 1979.


  • 5-Press Release: The 1996 Nobel Prize in Physiology or Medicine

  • 6-Nobel Lecture, December 8, 1996 Cellular Immune Recognition and the Biological Role of Major Transplantation Antigens

  • 7-Nobel Lecture, December 8, 1996 Cell Mediated Immunity in Virus Infections



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