Human anti-murine immunoglobulin responses in patients receiving monoclonal antibody therapy.

Human anti-murine immunoglobulin responses were assessed in serum from three groups of patients receiving murine monoclonal antibody therapy. Each of the three patient groups responded differently. Chronic lymphocytic leukemia patients demonstrated little or no preexisting murine immunoglobulin G-reactive antiglobulin prior to treatment, while the cutaneous T-cell lymphoma and melanoma patients demonstrated preexisting antiglobulin levels in the same range as those demonstrated in healthy controls. None of 11 chronic lymphocytic leukemia patients receiving the T101 monoclonal antibody demonstrated an antiglobulin response, whereas all four of the cutaneous T-cell lymphoma patients receiving the same antibody developed increased levels of antiglobulins. Three of nine malignant melanoma patients receiving the 9.2.27 monoclonal antibody showed an increase in antiglobulin titers. In patients developing antiglobulin responses, the response was rapid, typically being detectable within 2 weeks. The antiglobulins were primarily immunoglobulin G and, with the exception of a single melanoma patient in whom the response appeared to have a substantial 9.2.27-specific component (i.e., antiidiotype), were cross-reactive with most murine immunoglobulin G preparations tested. This pattern of results suggested that the antiglobulin was a secondary immune reaction with elevation of the levels of preexisting antiglobulin which was cross-reactive with the mouse antibody administered. While the presence of serum antiglobulin would be expected to present major complications to monoclonal antibody therapy, no clinical toxicity related to antiglobulin responses was observed in these patients, and no inhibition of antibody localization on tumor cells was seen.

Evaluation of alternative methodologies for the generation of murine monoclonal anti-idiotypic antibodies to human B cell leukemias and lymphomas.

The standard immunization procedure for the development of monoclonal antibodies to human malignant B cell idiotype immunoglobulin in our laboratory consists of intraperitoneal immunization with 50-100 micrograms of purified immunoglobulin followed 7 days later by intravenous immunization with an equal quantity of protein. In order to shorten the process and decrease the amount of idiotypic immunoglobulin necessary for successful immunization, we have evaluated 2 alternative immunization procedures. When immunized by the standard method, the percentage of hybridomas demonstrating anti-idiotype activity was 0.3-1.0%. In order to increase the proportion of anti-idiotype hybrids tolerance to the constant regions of human IgM was established by intraperitoneal administration of disaggregated human gamma globulin 14 days prior to immunization of both male and female mice. The percentage of wells with anti-idiotype activity rose to 16-52% in tolerant male mice. The percentage of anti-idiotype hybrids generated was significantly lower in tolerant female mice. To accelerate the process of anti-idiotype development, a single intrasplenic immunization with soluble idiotype IgM was also evaluated. No anti-idiotype or anti-IgM secreting heterohybrids were formed out of nearly 1400 wells seeded in 3 separate fusions using soluble IgM. When the idiotype IgM was immobilized onto protein A-Sepharose, and then injected intrasplenically, approximately 1% of the wells seeded showed anti-idiotype activity. Thus, a single intrasplenic immunization with immobilized immunoglobulin resulted in significant time saving, while prior tolerization may greatly increase the percentage of anti-idiotype hybrids.