Suppression of murine allogeneic cell interactions by sex hormones.

Investigations have been carried out on the action of several steroid hormones on lymphocyte functions in inbred strains of mice. The recognitive, proliferative and effector phases of allogeneic cell interactions in vitro were assessed using a mixed lymphocyte reaction (MLR) and cell-mediated lympholysis (CML). In MLR containing Balb/c (responder) and C57bl/6 (stimulator) splenocytes DNA synthesis was markedly reduced in the presence of progesterone, cortisol or estradiol. In CML, progesterone and estradiol (1-5 microgram/ml) blocked in vitro generation of cytotoxic lymphocytes, while cultures with cortisol were partially inhibited. None of these hormones suppressed the cytotoxic activity of previously sensitized effector cells generated in vitro. Cultures containing testosterone expressed both normal DNA synthesis in MLR and cytotoxic activity in the CML test. These findings suggest a selective pattern of immunosuppression by sex hormones which may be important in preventing graft rejection or graft-versus-host interactions which may arise as a consequence of fetal engraftment during pregnancy.

Mitogen stimulation of splenocytes from mice infected with scrapie agent.

Spleen weights and mitogen responsiveness of splenocyte cultures from scrapie agent-infected and control-inoculated mice were compared over two-month periods following inoculation. Splenocytes from Swiss, C57B1, and BALB/c mice were stimulated with the T (thymus-derived) cell mitogens phytohemagglutinin or concanavalin A, the B (bone marrow-derived) cell mitogen bacterial lipopolysaccharide, or pokeweed mitogen, a stimulator of both T and B cells. Although significant splenomegaly was associated with scrapie infection, we failed to observe any significant differences in the activation of experimental and control cells. Studies with BALB/c mice suggested the possibility, however, that with both phytohemagglutinin and lipopolysaccharide, specific decreases in lymphocyte activation might occur with more optimal culture conditions. The data are consistent with the idea that the scrapie agent stimulates only subtle immunological changes within the host as it destroys the cells of the central nervous system.

Factor 8 detection by hemagglutination inhibition: hemophilia A and von Willebrand's disease.

Factor VIII activity was detected immunologically in both the serums and plasmas of 14 normal individuals and 14 patients with hemophilia A. A hemagglutination-inhibition test with rabbit antibody to highly purified (10,000-fold) factor VIII from humans was used. Serums and plasmas from eight patients with von Willebrand's disease showed little or no factor VIII activity in this test, an indication that the test may serve as a specific assay for differentiation between von Willebrand's disease and hemophilia A.