There is increasing evidence that some models of immunologically mediated murine embryo demise involve nonspecific lytic effector cells. In this paper, we use two double stranded synthetic RNAs, known as potent interferon inducers and NK cell activators, the Poly (I). Poly (C) and the less toxic Poly (I). Poly (C12U). These polynucleotides enhance fetal resorption rates in both resorption prone and none-resorption prone strains of mice. We have studied the kinetics of the phenomenon, and observed an anti-implantation-like effect of early injection during early pregnancy. The abortifacient effects can be adoptively transferred to naive recipients by spleen cells from Ds RNA injected donors. Such effects are abrogated if the cells are pretreated with anti-NK cell antiserum. The relevance of these findings to the survival of the conceptus is suggested.

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We investigated the nature of deficient antibody responses to SRBC in stable, fully allogeneic bone marrow chimeras. No evidence for a suppressor cell-mediated mechanism was found. Chimera spleens possessed adequate numbers of antigen-reactive B cells to produce a normal antibody response. Using separated chimera cell populations and soluble helper factors, we assessed the functional capabilities of chimera B cells, T cells, and macrophages. Our data suggest that the failure of allogeneic chimeras to produce antibody is not the result of impaired B cell, T cell, or macrophage function, but rather that it is due in ineffective cellular interactions that normally result in the generation of helper factors. In vitro stimulation of chimera macrophages with LPS, and of chimera spleen cells with Con A, resulted in the release of soluble helper factors that were capable of fully restoring chimera B cell responses.