Reticuloendothelial function in pregnancy.

Several clinical observations suggest that pregnancy alters reticuloendothelial (RES) function. Pregnant women are more susceptible to paralytic poliomyelitis'," and influenza,' and there is a direct relationship of multiparity to bacteruria.' Pregnancy also appears to be the state most likely to prepare a human being for a generalized Shwartzman reaction. Measurements of RES function in pregnant animals are few and have yielded diverse results; Engels7 reported pregnant rats did not clear their circulations of thorium suspensions as rapidly as controls, while McKay' described enhanced clearances of carbon particles in pregnant rats when compared to normals. Two observations suggest that pregnancy depresses the ability of the RES to clear clotting factors from the blood: 1) Agents which caused RES blockade prepared an animal for a generalized Shwartzman reaction ;9 2) only one dose of meningococcal endotoxin was necessary to induce a generalized Shwartzman reaction in a pregnant rabbit.'0 Granulopectic activity, which refers to clearance of circulating particles such as bacteria, colloidal carbon and gold, has been used to evaluate RES function. Benacerraf, et al. have studied the behavior of aggregated human serum albumin in the mouse, rat, rabbit, and guinea pig, and found that clearance of aggregated albumin obeys the same laws that govern the clearance of other colloidal suspensions from the blood.'1 The present investigation was undertaken to determine the effect of pregnancy upon RES function in three animal species by studying blood clearances of injected aggregated human serum albumin.