indlan ,7. P#diat. 39 : 87. 1972

FIRST I N T E R N A T I O N A L CONGRESS OF I M M U N O L O G Y

W a s h i n g t o n , D . C . A u g u s t 1-6, 1971

AN OBSERVER'S REPORT

The Congress was organised with the main objective of reviewing the ex- plosive progress in the broad discipline of immunology and indicating trends for future investigations. The enormity and breadth of current immunology made this an almost impossible task, but the thoughtful planning which went into the organization of this Congress succeeded to a large extent in achieving the objec- tive.

There were no free papers. Fifteen symposia and sixty-four workshops were

held, which encompassed the entire range of basic and applied immunology.

Sympos ia

In the symposium on The Structure and Genetics of Antibodies, the problems of antibody diversity, the relationship of antibody structure to function, the evolu- tion of immunoglobulins, and the rela- tionship of genetic variation to antibody

specificity were tackled. The need for concurrent analysis of large numbers of immunoglobulin chains and for examina- tion of sal,ent aminoacid sequences near disulfide bonds was stressed. This would laelp in the construction of a 3-dimensio-

nal picture at atomic resolution and give us an idea of the overall shape as well as

the details of folding near active sites. Investigation of allotypes provides an in- light into gene expression, and coevolu- tion of multiple genes. In the Lympho- cyte Membranes session, the differences in T and B lymphocytes regarding their

surface membrane properties including the presence of immunoglobulin receptors and complement C' 3 receptors on B type, were discussed. The role of cell membrane in ant igen binding, and

consequential recognition for immune

response or tolerance was suggested. Electron microscopy, immunofluorescence and inhibition of cell activity by anti-Ig sera were used for these investigations. The Role of Antibodies and Complexes in Immune Tissue Damage was discussed by delineating the initiating factors

which trigger and accelerate injury, and it was suggested that this may be an anaphylactic event. I t was speculated that these processes may also be operative

in atherosclerosis and multiple sclerosis. The molecular basis for stimulation of cells to release injurious constituents--

anaphylatoxin, chemotactic agents, Fc

fragment of allied Ig molecules and the bound fragment of complement, was

outlined. The significant influence of cyclic AMP and second messenger system was suggested. There was some

description of the nature and importanc e of antibodies directed against tissues, such as in the Goodpasture syndrome.

The Structure of Immunoglobulins with special reference to combining sites and chain interactions, was studied with the help of X-ray diffraction techniques app!ied to homogeneous crystalline Igs. Methods involving modification of aminoacid sequence and therapy anti-

88 INDIAN JOURNAL OF PEDIATRICS

body activity have previously helped ~in this direction. Affinity binding, anti- hapten antibodies and ligand binding myeloma proteins have been used in these studies. The next symposium dealt with Cell Co-operation in the Immune Response. The interaction of the two distinct cell lineages (derived from the thymus or bursa) in the boy's response to specific antigenic determinants was presented through studies on thymecto- raised, irradiated and reconstituted mouse system. It was disputed if T cells carry a single or multiple specificities. The relative importance of steroid-sensi- tive and steroid-resistant lymphocytes was elegantly presented. One speaker showed results in which, using the so- called thymus independent antigens and homocytotroFic antibodies, thymus derived ceils showed depression of anti- body formation instead of co-operation. The exact way in which co-operation occurs is not clear. It was suggested that it may operate through a judicious presentation of antigen, by cell surface interaction, elaboration of substances without immunological specificity, or more than one factor may be operating. The basic mechanisms through which cell-mediated immunity operates, was the subject of another symposium. Following activation of effector lympho- cytes, an elaborate and complicated chain of events is sets off increase in turnover of membrane phospholipids, acetylation of histones, increased synthesis of RNA, increase in binding of acridine orange or actinomycin to the nucleus, increase in endocytosis and redistribution of lysosomal enzymes, cell enlargement, in- corporation of thymidineinto DNA and mitosis. Blast transformation, cytotoxi-

VOL. 39, No. 290

city, macrophage migration inhibition~ inhibition of growth of target cell and several functions may then take place, which become the in vitro indicators of cell mediated immunity. Besides these questions about the quality, the number of lymphocytes committed to a single antigen was discussed. This was thought to vary, being of the order of 1-2% in the case of PPD. The number may also change with repeated immunization in the case of some antigens (such as PPD again) and not for others (histocompati- bility antigens).

The Genetic control of Immune Responsiveness was the subject of a symposium. The degree, site and type of control varies in different species, and the role of histocompatibility alleles was considered important by Jerne. Cohn postulated a positive selection mechanism in which all clones would die unless they undergo immunogenic encounter leading to differentittion and extended life. There was some evidence to indicate that the genetic differences may reside in the frequencies of monoscecific cell popula- tions in the bonemarrow and not of those in the thymus. The symposium on Transplantation in the Human addressed itself to fundamental questions of the nature and biological function of HLA histocompatibility system. It was con- cluded that the present serological methods are unable to distinguish between similar (crossreacting) but non- identical mutants, or there is a third site closely linked to LA and Four loci, which. is important for MLC activation and graft rejection. These postulations would explain the acceptance of grafts betweer~ identical siblings but not between HLA matched donors outside the sibship. The

FIRST INTERNATIONAL CONGRESS OF IMMUNOLOGY 89

significance of MLC as a basic pheno- menon in biology and in 'surveillance' was stressed, since MLC is not a secondary response and transplantation immunity is largely independent of heterophylic environmental stimulation. Complement has been thought to be important in antigen-antibody complex, mediation of cell injury, as a membrane binding agent on lymphocytes, besides its participation in the classical phenomenon of phagocytosis, histamine release from mast cells and platelets, and promotion of blood coagulation. The ultrastructure of complement molecules and the damage they produce, was presented. In addition, the genetic polymorphism, acquired and inherited defects in one or more components, and phlogogenic complement peptides were described.

In a clinically oriented symposium, the Manipulation of the Immune Response was discussed. The role of adjuvants in the precipitation of immune phenomena, the exciting field of cellular engineering or reconstitution of defi- ciency states by proteins or cells, and the methods for concentration of various subpopulations of cells were brought out. The ways in which anti-tumour immu,ity can be potentiated, e.g. by contact sensi- tizers, nonspecific and specific immune stimulation in leukaemia, attachment of chemotherapeutic agents or radioactive compounds to tumour specific antibody for a concentration of the agent at the turnout site, and the use of mycobacteria, its products or poly-rA: poly-rU, was outlined.

Workshops These provided an intimate and

informal forum for discussion of a parti-

cular topic by 20-30 invited people most interested in the subject. 64 workshops were held; 16 on each day. The topics covered included granulocyte functions in immunological reactions, immune deficiency diseases, catabolism of immu- noglobulins, immunology of gonorrhoea and syphilis, radiation effects on the lymphoid system and its functions, aUo- types, antibody to enzymes, blood group antigens, nucleic acid as antigen, cross- reactions between microbial and tissue antigens, neutralization of virus by anti- body, immunology of reproduction, autoimmune diseases, immunological activation of the kinin forming system, antibody combining sites, immunopatho- genesis of glomerulonephritis, immune capabilities oi germfree animals, phylo- genetic aspects of immunity, immuno- globulin biosynthesis, cellular kinetics of immune response, kinetics and thermo- dynamics of antigen-antibody interac- tions, genetic control of immune respon- siveness, cytotoxic activities of lympho- cytes, chemotaxis of leukocytes, immuno- logical disorders of inbred strains of mice, biochemistry of complement, bacterial endotoxins, immunity to parasites, immunosuppression, transfer of immunity with cell free extracts, idiotypic antibody, thymic hormones, histology of immune response, complement biology in disease, histocompatibility antigens, soluble medi- ators of delayed hypersensitivity, patho- genesis of runting syndrome, purification and characterisation of allergens, secre- tory immunoglobulins, ultrastructure of immunoglobulins and antibody-antigen complexes, established lymphocytic cell lines, allergic release of amines from cells, and homogeneous antibody and myeloma proteins with antibody activity.

90 INDIAN JOURNAL OF PEDIATRICS

Part i c ipat ion f r o m Ind ia Doctors Sudha, Gangal, Q.Z.

Huss~n and R.K. Chandra from India participated and presented their view points and data in various sessions. Work related to hepatitis-associated antigen and depressed cellular immunity in Indian childhood cirrhosis, and that

VoL. 39, No. 290

related to granulocyte function in malnu- trition attracted particular notice, and is included in the Progress of Immunology (Academic Press, New York and London), which is an excellent extensive report on the International, Congress.

The next Congress is likely to be held in England in 1974.

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