LISTERIA-MONOCYTOGENES INFECTION IN PREGNANT MICE - ABNORMALITIES IN THE FUNCTION OF NONADHERENT ACCESSORY LIGHT DENSITY DENDRITIC CELLS

Pregnant A/J mice were found to be more susceptible to the lethal effe ct of Listeria monocytogenes bacteria than virgin females, However, du ring the first four days of post-infection there was no difference in the elimination of Listeria from the spleens of pregnant and virgin mi ce. This suggests that the increase in the susceptibility of pregnant mice to pathogenic activity of L. monocytogenes was related to the dim inution in Listeria-specific cellular reactions, Indeed, we found that non-adherent light density dendritic cells (DCs) from pregnant mice s howed a marked reduction in the ability to form clusters with L. monoc ytogenes immune T lymphocytes and it is known that cell cluster format ion between antigen presenting cells (APC) and responding T cells is r equired for antigen recognition as well as for cell proliferation, DCs from pregnant mice also demonstrated the decrease and an instability in the expression of H-2 class II molecules which play a crucial role in the recognition of exogenous antigens. The abnormalities demonstrat ed in the function of the light density dendritic cells from the splee ns of pregnant mice could compromise cellular reactions to L. monocyto genes bacteria possibly resulting in increased susceptibility of pregn ant mice to experimental listeriosis,