Immunological suppression of idiotypic specificities

Mechanisms of tumour cell escape encountered in treating lymphocytic leukaemia with anti-idiotypic antibody

Four patients with chronic lymphocytic leukaemia were treated by one or more infusions of polyclonal antibody specific for the immunoglobulin idiotype expressed on their leukaemic cells. The antibody was in the form of IgG from sheep antiserum. Three of the 4 cases showed a significant fall in blood lymphocyte count. On one occasion most of the residual circulating lymphocytes were apparently dead. However on all occasions the cell counts rebounded to near pre-infusion levels within one week. Viable lymphocytes recovered from the blood after infusion always showed evidence of antigenic modulation: a diminished level of surface idiotype in a patched distribution, with an accompanying refractoriness to lysis by anti-idiotype plus complement. When cultured in vitro blood lymphocytes from three of the four patients revealed an appreciable export of idiotypic Ig. These 3 patients showed plasma levels of idiotypic Ig up to 400 micrograms ml-1, reduced by plasma exchange prior to infusion. The fourth patient had a level of less than 4 micrograms ml-1, and was the only one in whom free antibody could be found in the plasma after infusion. These cases demonstrate two major factors which thwart antibody attack on leukaemic cells--extracellular antigen and antigenic modulation--as well as problems relating to sparseness of surface antigen, recruitment of effectors, and exhaustion of effectors.

Independent regulation of serologically distinct idiotypes in F1 hybrid mice

We have investigated the regulation of expression of two distinct intrastrain cross-reactive idiotypes, CRIA and CRIC , characteristic of anti-p-azophenylarsonate (anti-Ar) antibodies of the A/J and BALB/c strains, respectively, in (BALB/c X A/J)F1 ( CAF1 ) mice. Such hybrid mice were found to synthesize antibodies with each idiotype when immunized against the Ar hapten group, although the expression of each was significantly reduced as compared with the parental strain. CAF1 mice were pretreated with idiotypic-specific antibody reagents and subsequently hyperimmunized against the Ar hapten. Analysis of the idiotypes present in immune sera showed that suppression of either CRI did not concomitantly suppress the expression of the other. Alteration of the expression of one idiotype was not, however, without influence on the other; the expression of CRIC was markedly enhanced in mice suppressed for CRIA.

Naturally occurring autologous anti-idiotypic antibodies. Participation in immune complex formation in selective IgA deficiency

50% of individuals of selective IgA deficiency have high serum titers of antibody to bovine proteins, and high levels of circulating immune complexes that contain bovine antigens. Because in animal studies, immunization with antigen-antibody complexes is a very effective means of producing anti-idiotypic antibodies, we sought such autoantibodies in two sera known to have large amounts of anticasein. After IgG isolation and two-stage affinity chromatography, IgG-like material (molecular weights of H and L chains on SDS-PAGE), with binding activity for the F(ab')2 of anticasein were isolated from both sera. Pooled human gamma globulin or IgG myeloma proteins did not inhibit binding of specific anti-anticaseins to the corresponding anticasein, but sodium caseinate did block this binding (by 80 and 95%) indicating that most of these autoantibodies have affinity for the casein-binding site. Naturally occurring anti-idiotypic antibodies have been difficult to conclusively demonstrate in human sera; consequently, these experiments provide evidence of a unique model which may be used to explore the network theory of immunoglobulin regulation in humans.

Cellular interactions in immune regulation. Hapten-specific suppression by non-T cells and T cell mediated reversal of suppression

The ability of lymphoid cells from immunized animals to regulate the response of naive B ceils to the immunizing hapten was studied. Mice were immunized with trinitrophenylated (TNP) bovine gamma globulin (BGG) in complete Freund's adjuvant, and their spleen cells were examined in vivo and in vitro for the presence of specific inhibitory activity. This activity was found to peak 1 wk after immunization, was active against TNP on both T-dependent (BGG) and T-independent (Ficoll and polyacrylamide beads) carriers, and was demonstrable both by mixed cell transfers and mixed cell culture experiments. In in vitro studies, it was shown that the inhibition of the response to TNP- polyacrylamide beads by immune spleen cells was mediated by a non-T cell, possibly a B cell, because the suppressor activity was enriched in a purified B cell preparation. A role for macrophages was not formally ruled out. A specific suppressor factor was produced in vitro by immune spleen cells cultured in the absence of antigen. The suppressor activity was modulated by T .cells because elimination of T cells from the normal spleen cell population decreased suppression; elimination of T cells from the immune spleen cell population did not effect suppression, but elimination of T cells from both the normal and immune spleen cell populations allowed the expression of marked specific suppression. Thus, T cells present in the normal spleen cell population augment the degree of suppression, whereas T cells present in the immune spleen cell population decrease the degree of suppression; that is, T cells present in the immune spleen cell population had the ability to specifically abrogate suppression ("abrosuppression") in a T-independent immune response. It is proposed that the response to a T- independent antigen is regulated by specific suppressor activity generated by a non-T cell and augmented by the interaction of this cell with a T cell. The suppressor activity can be blocked by a specific abrosuppressor T cell. It is suggested that, because suppressor activity appears dominant in the naive state of the immune system, the induction of specific abrosuppressor activity may be essential if an immune response is to take place.

Immune response genes control T killer cell response against Moloney tumor antigen cytolysis regulating reactions against the best available H-2 + viral antigen association

Cytolytic T lymphocytes (CTL) specific for the virus-induced and leukemia-associated Friend, Moloney, Rauscher (FMR) antigen are easily detected in the spleens of primary and secondary stimulated H-2b or H-2d mice. They react, respectively, with H-2Db + FMR and H-2Kd + FMR; Dd and Kb never being involved. On the other hand, recombinant (KbDd) mice are relatively low responders that produce CTL only after secondary stimulation. Competition and blocking experiments with monospecific anti-H-2 antibodies have demonstrated that on the same H-2b tumor cells, C57BL/6 (H-2b) lymphocytes recognize Db + FMR, whereas B10.A(5R) lymphocytes recognize Kb + FMR, the restriction cannot, therefore be explained by a specific association of viral molecules with certain H-2 products. The CTL response of (B10 X 5R)F1 hybrids is (a) easily detected in primary reaction, the high responder anti-FMR phenotype being dominant and (b) directed against Db + FMR, F1 mice being low responder against Kb + FMR like the B10 parent. These results suggest that a D region-associated immune response gene controls the cell-mediated anti-FMR reaction, the best available H-2 + FMR antigenic association being chosen by CTL precursors.