The guinea pig i-region. A functional analysis of Ia-Ir associations

Serological and genetic identification of a bovine B lymphocyte alloantigen system

A two-colour fluorescence microcytotoxicity test was used to screen antisera for antibodies specific for bovine B lymphocytes. A total of 114 cattle alloantisera were screened against peripheral blood lymphocytes from 100 unrelated individuals. Anti-B lymphocyte activity was detected in 47 antisera. Cytotoxic antibodies to antigens other than B lymphocyte specific antigens were removed by absorbing the antisera with buffy coat cells or platelets isolated from whole blood. Selected antisera were used to type paternal half-sib families. The presence of a polymorphic, MHS-linked antigen system on B lymphocytes was demonstrated. The tissue distribution and MHS linkage of these antigens suggests this system is analogous to the class II or Ia antigens of other species.

Major histocompatibility complex class II antigen expression during potentiation of line-10 tumor immunity after intralesional administration of bacillus Calmette-Guérin

Intralesional injection of BCG into an established line-10 hepatocellular carcinoma in the strain-2 guinea pig causes regression of the tumor and induction of line-10 immunity. We found that the animals were already protected for a second challenge with line-10 tumor cells 7 days after BCG treatment. We studied whether this early induction of immunity was correlated with the expression of MHC class II antigens on line-10 tumor cells and was correlated with an increased expression of MHC class II antigens on leukocytes in the primary tumor and in the regional lymph node (Ln. axillaris accessorius). The MHC class II antigens and the leukocyte subpopulations were measured with monoclonal antibodies and flow cytofluorometry. In the draining lymph node the number of nucleated cells increased about 10-fold during the first 5 days after intralesional injection of BCG. At this time the MHC class II antigen expression of these cells was increased from 21%-32% in the naive controls to 39%-53% in animals with BCG-treated tumors. This implies that the number of MHC-class-II-positive cells increased about 20-fold in the draining lymph node. Surprisingly, the increase in percentage of MHC-class-II-antigen-positive cells was mainly due to an increase of IgM-positive B cells from 8%-11% to 22%-41% and an increase of IgG-positive B cells from 7%-27% to 25%-44%. In the tumor, BCG treatment induced a small increase of MHC-class-II-antigen-positive cells from 11%-12% to 15%-20%. Probably this increase came not from tumor cells but mainly from a BCG-induced infiltration of mononuclear cells, as an increase of T cells from 14% to 20%, an increase of macrophages from 8% to 18%, and an increase of B cells from 0 to 6% was observed. We conclude that the potentiation of anti-(line-10 tumor cell) immunity correlated with a 20-fold increase of MHC-class-II-antigen-positive cells in the lymph nodes and a small increase in the number of MHC-class-II-antigen-positive tumor-infiltrating cells.

Comparative reactivity of anti-Ia monoclonal antibodies in man and laboratory animals

Sixteen murine monoclonal antibodies (MAb), reactive with HLA-DR, DR + DP or DR + DQ, were tested, using indirect immunocytofluorescence, for their reactivity with peripheral blood mononuclear cells (PBMC) from the dog, cat, guinea pig, sheep, rabbit and rat. In addition, the MAb were evaluated for inhibitory activity in the canine mixed lymphocyte culture (MLC). Fourteen of 16 MAb reacted with canine PBMC. There was a greater tendency for DR + DP reactive MAb to inhibit canine MLC and subsequently react with PBMC of the guinea pig, sheep, and, cat. MAb failing to block the canine MLC were generally nonreactive with guinea pig PBMC (7 of 9 nonreactive) suggesting the guinea pig may be a useful model to study the functional relevance of specific Ia molecules. One MAb, H81.98.21 (reactive with HLA-DR) blocked canine MLC and reacted with PBMC from all species tested suggesting the determinant it recognized to be very well conserved in nature.

Immunogenetic studies of respiratory anaphylaxis in selectively bred guinea pigs. Inheritance of atopy, linkage to MHC-complex

The genetic and immunological basis of respiratory anaphylaxis was studied in two strains of guinea pigs selectively bred for either high or low respiratory anaphylactic response to inhalation of ovalbumin. Individuals of the parental strains, F1-hybrids and backcross offspring were examined for class II MHC type and asthmatic response to ovalbumin. Analysis of the results revealed an association of asthma phenotype and MHC class II type. Apart from the gene(s) in the MHC several other genes seem to be involved in the control of guinea pig asthma.

Invariant proteins associated with guinea-pig Ia antigens

Analysis of guinea-pig Ia immunoprecipitates by two-dimensional gel electrophoresis demonstrated the specific association of Ia molecules with several types of invariant proteins. These include a 33,000 mol. wt basic protein homologous to murine invariant chain (Ii), and a set of 34,000-36,000 mol. wt proteins more acidic than Ii (acidic invariant chain). Two 23,000-25,000 mol. wt non-polymorphic proteins with pIs of 6.0 and 6.5 were also observed in association with Ia, as was a basic protein of mol. wt 42,000. Pulse/chase studies using [35S]methionine demonstrated that Ii, but not acidic invariant chain, was associated with newly synthesized Ia molecules. The amount of 35S-Ii decreased greatly throughout the chase period. 35S-acidic invariant chain was clearly present in Ia precipitates by 30 min after Ia synthesis, but was not detected 4 hr after synthesis. Only acidic invariant chain was associated with mature Ia antigens bound by the lectin Ricinus communis I. Our results indicate that guinea-pig invariant proteins are differentially bound by Ia molecules during maturation of Ia alpha- and beta-chains, and suggest that acidic invariant chain could be a processed form of Ii.

Production and properties of monoclonal antibodies to guinea pig Ia antigens

Although the use of monoclonal antibodies to characterize the Ia antigen system is still in its infancy, the usefulness of this approach is clearly apparent. Since xenogeneic immunization can be used to generate these antibodies, the chances are good that a greater variety of Ia types and determinants will be detected compared to those detected with conventional alloantisera. In addition, the advantages of unlimited quantity and constant specificity allow a much greater degree of standardization than was previously possible. Finally, monoclonal antibodies open up lines of investigation, such as the examination of correlations between the monoclonal antibody's inhibition of T-cell proliferation and the antibody's corresponding Ia epitope-binding characteristics, that it would be impossible to approach using conventional alloantisera.

Nature of the antigenic complex recognized by T lymphocytes. VIII. Specific inhibition of the stimulatory capacity of antigen-pulsed hapten-modified peritoneal exudate cells by anti-hapten antibody

When macrophages which were pulsed with soluble protein antigens and then modified with 2,4,6-trinitrobenzenesulfonic acid (TNBS) were cultured with primed T cells in the presence of anti-2,4,6-trinitrophenyl (TNP) antiserum, a marked inhibition of the T cell proliferative response specific for the soluble protein antigen under study was observed. Inhibition of the proliferative response required that the protein antigen under study be easily susceptible to conjugation with TNBS. A lag period of 1-3 h must elapse following pulse exposure to the protein antigen and prior to TNP modification for anti-TNP antibody to exert an inhibitory effect, which suggests that processing of antigen in an intracellular site might occur with subsequent reexpression of antigen on the macrophage surface. It was hypothesized that anti-TNP antibody inhibits T cell proliferation by capping and shedding of TNP-modified determinants of the nominal antigen as well as TNP-modified cell surface proteins from the macrophage membrane. The failure of others to demonstrate an effect of anti-antigen antibody on T cell activation can best be explained as secondary to the low density of antigenic determinants on the macrophage membrane with resultant low-affinity binding of antibody to antigen.

The reaction of xenogeneic and monoclonal antisera with Reed-Sternberg cells

Xenogeneic antisera have been prepared against human monocytes, B lymphocytes and T lymphocytes. The reactivity of these antisera against a variety of normal and neoplastic cells is described. Reed-Sternberg cells from three cases of Hodgkin's disease failed to react with xenogeneic anti-T and anti-monocyte sera, but reacted with an anti-B serum. A further three cases were examined with monoclonal antibodies. Negative results were obtained with monoclonal anti-T and positive results were given by monoclonal antibodies directed against DR and HLA antigens.

The peritoneal antigen-presenting macrophage: control and immunogenic properties of distinct subpopulations

The control of the immunogenic antigen-presenting capacity of different subpopulations of thioglycollate-induced peritoneal macrophages had been investigated. The experiments revealed the existence of two major subpopulations of macrophages, only one of which was highly efficient in educating antigen-specific T cells. The other subpopulation, while highly phagocytic, was devoid of antigen-presenting capacity. Further analysis, using specific antisera directed at H-2I region gene products, revealed that the immunogenic antigen-presenting population expressed H-2I region-controlled membrane antigens. Searching for cellular elements which control the differentiation of this antigen-presenting macrophage subpopulation, it was found that its function was strictly controlled by T cells. T cell-deficient mice (nu/nu) failed to generate a functional antigen-presenting macrophage subpopulation. Transplantation of mature T lymphocytes to T cell-deprived mice restored the immunogenic function of their antigen-presenting macrophage subpopulation. Transplantation of mature T lymphocytes to T cell-deprived mice restored the immunogenic function of their antigen-presenting macrophages. The results obtained suggest the existence of heterogeneity of functions among macrophage subpopulations and add a new regulatory function for T cells.