Antitumor immunity in B-lymphocyte-deprived mice. II. In vitro studies

The repertoire of anti-TNP antibodies in mice neonatally suppressed with anti-IgM

Previous studies have shown that mice immunized with TNP-Ficoll when young, adult, or aged expressed different repertoires of anti-TNP antibodies. The aim of the present study was to find out whether this age-related nonrandom progression was driven by antigen, and whether it was regulated by the immune network through surface-Ig receptors on B lymphocytes. The approach utilized was to block receptor expression on B lymphocytes of mice by the chronic administration of anti-IgM from birth for approximately 1 year, and then compare their subsequent antibody response to that of age-matched control animals. The results obtained have shown that the age-dependent shift in the anti-TNP repertoire expressed could take place in animals whose B lymphocytes were blind to antigen and anti-id for the greater part of their lives and thus suggest that the regulatory events responsible for this shift may be (surface Ig) receptor independent.

Immunity to lymphocytic choriomeningitis virus in B cell-depleted mice: evidence for B cell and antibody-independent protection by memory T cells

Immunity against lymphocytic choriomeningitis virus (LCMV) in anti-IgM-treated B cell-depleted mice was evaluated. We found that the following immune phenomena were independent of antibodies: the generation of virus-specific cytotoxic T cells; the footpad swelling response against locally injected LCMV; natural killer cell activity basic levels or after LCMV or poly(I) X poly(C) stimulation; immunopathologically mediated LCM after primary intracerebral inoculation; immunological memory in LCMV-immune mice assessed by immune protection against LCM after intracerebrally injected virus or as resistance against the local footpad swelling response to LCMV. This study demonstrates that humoral immunity plays no crucial role in immune protection and immunopathology in murine LCMV infection and suggests that protective memory T cell function is B cell and antibody independent.

Colorectal carcinoma in a rat model: suppression of tumour development and altered host immune status following treatment with anti B-lymphocyte serum

The rate of colonic tumour development and immune capability in rats whose B-lymphocyte function was suppressed by injections of rabbit anti-rat IgM and also given the carcinogen dimethylhydrazine (DMH) were studied. Four rat groups were arranged to receive either DMH + anti-IgM, DMH + normal rabbit serum (NRS), saline + anti-IgM, or saline + NRS. Tumour weight, blood and mesenteric lymph node B-lymphocyte numbers, in vivo allograft response, in vitro lymphocytotoxicity, and leucocyte migration inhibition response (LMI) were recorded fortnightly. Tumour induction was delayed in the DMH + anti-IgM (treated tumour) group, which developed less tumour than the DMH + NRS (untreated tumour) group (p less than 0.001). Spleen cell lymphocytotoxicities were depressed in treated rats when compared to either the saline + anti-IgM (treated control) rats or the untreated rats (P less than 0.02), whereas anti-IgM treatment suppressed lymphocytotoxicity responses in control rats (p less than 0.05). The untreated tumour rats were tumour immune by LMI; however, the treated tumour rats did not express this in vitro tumour immunity. The B-lymphocyte levels in the mesenteric lymph nodes of untreated tumour rats increased with tumour induction (p less than 0.05), whereas in the treated tumour rats B-lymphocyte levels were not similarly stimulated.

Anti-tumor immunity in B-lymphocyte-deprived mice. III. Immunity to primary Moloney sarcoma virus-induced tumors

Tumor induction and immunity to tumors were studied following the injection of Moloney sarcoma virus (MSV) into mice whose B-lymphocyte functions had been suppressed by the chronic administration of anti-IgM antibodies. Two preparations of MSV were used; one which gives rise to tumors which uniformly regress in normal adult mice, and another which elicits progressively growing tumors in the majority of recipients. The tumor incidence, mean tumor size, and tempo of regression were not modified by treatment with anti-IgM. However, whereas tumors induced by the regressor virus were all rejected in 19 NRG-treated and 29 untreated recipients, continued growth was obtained in 2 of 23 B-lymphocyte-deprived mice. Furthermore, in 9 additional mice from this group, apparent rejection was followed by tumor recurrence at the site of the initial tumor. Continued growth was accompanied by widespread metastasis. These tumors were freely transplantable to normal syngeneic recipients. Metastasis and transplantability were also detected in 7 of 24 anti-IgM-treated mice given progressor virus, but were not seen in the control animals. Recurrence and metastasis was obtained despite the presence of high levels of specific cytotoxic T lymphocytes in the spleen. It is concluded that B lymphocytes or their products play an essential role in host protection against MSV-induced tumors.