Studies on the resistance to tolerance induction against human IgG in DDD mice. I. Organ differences of tolerogen susceptibility and cellular sites responsible for the resistance

Immunosuppression by immunoglobulin deaggregation is not effective in reducing the anti-xenogeneic immunoglobulin response: experimental and clinical studies

A major complication of in vivo monoclonal antibody therapy in patients with cancer is the host's immune response to the administered xenogeneic immunoglobulin. We have performed parallel clinical and experimental studies to investigate the possibility that deaggregation of the therapeutic monoclonal antibody might render it non-immunogenic, or even tolerogenic, as has been suggested in several animal studies. Deaggregation of xenogeneic immunoglobulin has been shown by others to induce non-responsiveness in some ('susceptible') but not in other ('resistant') strains of mice. We have used an improved deaggregation method of size exclusion chromatography connected to FPLC and have developed a sensitive ELISA detection system to determine whether highly purified human immunoglobulin G (hIgG) monomers could be tolerogenic even to 'resistant' mice. However, our data show that all preparations of hIgG are immunogenic to 'resistant' mice, and that although deaggregation does significantly reduce the anti-hIgG response to 'susceptible' strains, tolerance is not induced. Concomitant administration of cyclosporin A and deaggregated hIgG had a additive effect in reducing the murine anti-hIgG secondary response. In clinical studies of patients with ovarian cancer who received in vivo immunotherapy with either iodine-131 (not aggregated) or yttrium-90 (aggregated) HMFG1 mouse monoclonal antibody, no significant difference was found between the immune responses to aggregated and non-aggregated murine immunoglobulin G. Our data suggest that deaggregation alone is unlikely to be useful in controlling the human anti-murine immunoglobulin G response in our outbred patient population, although in combination with an immunosuppressant it may be more effective.

Autostimulatory lymphoid cells in aging mice: induction of syngeneic host-versus-graft reaction by radioresistant adherent cells in normal recipients

When young (6-week-old) BALB/c and also young C57BL/6 mice were inoculated into footpads with spleen cells from normal, syngeneic, aged donors, their response to the inoculum resulted in the enlargement of popliteal lymph nodes (PLN). The degree of PLN enlargement increased as the age of donor mice increased up to age one year. Spleen and lymph node cell populations were highly effective in eliciting the PLN enlargement. Thymus cells and bone marrow cells were moderately effective, but erythrocytes were ineffective. Resident peritoneal exudate cells and spleen adherent cells were much more effective than a whole spleen cell population. The syngeneic response seems to be attributable to a host-versus-graft reaction, since the PLN response was not affected by 2000 rad irradiation of inoculum cells and since the nylon wool-passed spleen T cell population was ineffective as the stimulator. The response was significantly reduced 3 weeks after thymectomy of recipients. PLN enlargement was also observed in older (7-month-old) mice which received spleen cells of younger mice. In this case, however, the response is ascribable to a graft-versus-host reaction, since the inoculation of radiosensitive spleen T cells into footpads resulted in the PLN enlargement. On the other hand, such a stimulatory activity was not found in either lymph node cells or thymus cells. These results suggest that the antigenicity of adherent cells changes with age and that the change is discernible by spleen-locating and short-lived T cells of young mice.

Studies on the termination of immunological tolerance in the mouse thymus cell population after irradiation

Immunological tolerance in the mouse thymus cell population induced by the intravenous injection of deaggregated bovine gamma globulin was terminated by whole body irradiation. After irradiation, the weight of the thymus recovered biphasically, and the termination of tolerance occurred as early as in the first phase. Both Thy-1 antigen expression and helper activity of the thymus cell population in irradiated mice recovered in parallel with the recovery of the thymus weight. Sensitivity of the regenerating thymus cell to the tolerogen was not different from that of the normal thymus cell. The first phase of thymus regeneration may be caused by the proliferation and differentiation of relatively radioresistant and tolerogen insensitive precursors residing in the thymus. Tolerogen and/or immunogen reactive thymus cells may originate from the precursor.

Establishment and characterization of permanent murine hybridomas secreting monoclonal anti-thy-1 antibodies

hybridomas secreting anti-Thy-1 antibodies were produced by fusing cells of the mouse myeloma line P3-NSI/1-Ag4-1 (NS-1) with spleen cells from AKR/J mice immunized with C3H/Di thymus cells and by subsequent growth in tissue culture and selection of the hybrid cells. Two permanent hybridomas, 1B5 and 1aG4/C5, secreting antibodies of IgG3 subclass were isolated by repeated cloning of cells by dilution and in soft agar. Growth of the hybrid cell colonies depended on the presence of feeder cells; spleen cells at 1-2 x 10(6)/ml were most effective, then thymus cells at 1-4 x 10(6)/ml and peritoneal cells at a concentration 1-2 orders of magnitude lower. The two hybridomas were grown in vitro or vivo and their products were further analysed. In tissue culture in serum-free medium under the optimum conditions the supernatant from hybridoma 1B5 contained 0.07 mg/ml of antibodies and that from hybridoma IaG4/C5 had 0.26 mg/ml of antibodies, whereas ascites 1B5 contained 3.6 mg/ml and ascites 1aG4/C5 4.4 mg/ml of antibodies. A very low electrophoretic mobility of both antibodies facilitated their isolation. The specificity of the antibodies was tested in the cytotoxicity assay in the presence of complement and by the binding of isotopically labelled antibodies to thymus cells from A/Ph mice and other Thy-1.2+ strains and A.Thy-1.1 and AKR/J mie. Antibodies of clone 1aG4/C5 were specific for Thy-1.2+ cells, whereas antibodies of clone 1B5 at higher concentrations also reacted with Thy-1.1+ cells from the thymus and lymph nodes. Both antibodies killed more than 95% thymus cells and 60-70% lymph node cells in the cytotoxicity assay. The specificity of antibodies for T lymphocytes was confirmed in the functional test in which the antibodies eliminated the response of spleen cells to Concanavalin A but did not affect the response to lipopolysaccharide in the presence of complement.

Tolerance induction in mice selected for high or low antibody responsiveness

Induction of tolerance to bovine serum albumin was studied in mice selected for high (H) or low (L) antibody responsiveness and in their F1 hybrids. No high or low zone tolerances were obtained in H mice whereas L mice were susceptible to tolerance induction by the two schedules. H mice were immunized by repeated injections of tolerogenic BSA for low zone tolerance induction but not after the administration of a single high dose of tolerogenic BSA. Resistance to tolerance induction is dominant in F1 hybrids.