No abstract

The responses of spleen cells from male and female BALB/c mice were evaluated to determine if sex-related variations in immune expression could be found. The immunologic assays used included blastogenic responses to mitogens, and direct and indirect measurement of plaque-forming cells against particulate antigens. The results indicated that responses of spleen cells from young adult female mice were higher than those of males in all comparative tests. Newborn mice did not demonstrate the sex-associated immune differences; and among the weanling mice slight differences between male and female spleen cells responsiveness to mitogenic agents were observed. The blastogenic responsiveness of spleens from female BALB/c was greater at proestrus and metestrus, as compared to estrus and diestrus. The peaks of responsiveness corresponded to reported elevated levels of estrogen and pregnenolone during these phases of the cycle. Similar results were obtained with the IgM plaque-forming cell responses, which were also increased at proestrus and metestrus. This study supports a role of sex hormones in modulation of immune expression.

No abstract

An increase in prostaglandins (PGs) of the E series has been demonstrated in Moloney sarcoma virus (MSV)-induced leg tumors of 6-week-old BALB/c male mice. The level of the hormone has been shown to increase with the tumor diameter and decrease with tumor regression. At the peak of tumor size the tibial bones of the mice were considerably deformed, suggesting osteoclastic activity. The systemic calcium level was not elevated, indicating possible release of calcium into the local tumorous area. In mice treated with indomethacin the tumors failed to develop and PG levels were markedly lower. Tibial bones of treated mice were similar in appearance to those of control, non-tumorous mice. PG levels of DBA/1J mice bearing extensive Cloudaman S91 melanomas were not elevated and no bone deformation was seen. When contrasted with studies of immuno-depressed mice the results suggest that indomethacin acted in conjunction with and possibly to restore the PG-induced depression of the immune system in preventing tumor development. It is also hypothesized that indomethacin, by suppressing the PG-mediated calcium release from bone, could be operative in inhibiting tumor growth.

Spleen cells removed from C57Bl/6J mice bearing a methylcholanthrene-induced fibrosarcoma (MC-16) demonstrate suppressed responsiveness of phytohemagglutinin (PHA) and bacterial lipopolysaccharide (LPS) induced mitogenesis as compared to non-tumorous mice. A similar depression of PHA-induced mitogenesis was observed with spleen cells from C3H/HeJ mice bearing syngeneic mammary adenocarcinomas (C3HBA). The administration of indomethacin, a non-competitive irreversible prostaglandin (Pg) synthesis inhibitor, (75 or 100 mug/mouse, IP) on an alternate day basis to groups of tumor-bearing mice of both strains, significantly enhanced immune cell responsiveness to mitogenic stimulation. The addition of indomethacin (10 mug/ml) to cultures of spleen cells from these tumor-bearing mice, as well as to DBA/1J mice bearing the Cloudman S-91 melanoma, enhanced spleen-cell responsiveness to mitogen-induced DNA synthesis by as much as 156%. Indomethacin administration in vivo or in vitro had no significant effect on mitogen-induced DNA synthesis of spleen cells from non-tumor-bearing animals. It is hypothesized that tumors, or tumor-cell antigens, increase Pg production of a population of spleen cells, and that the increased Pg content of the spleen may be important in controlling immune responsiveness in mice.