Immune complexes (ICs) and pregnancy. Pregnancy as an IC-state or IC-disease and the influence of IC-diseases on pregnancy.

The immunologic tolerance of the fetoplacental allograft by the maternal immune system is still poorly understood. Recently published studies resulted in a widely publicized controversy on the presence or absence of immune complexes (ICs) in normal and abnormal pregnancies. The present review is an attempt to analyze presently known data critically and to reach subsequently derived conclusions which may be relevant to the understanding of the immunologic phenomenon of pregnancy. Pregnancy may represent an immune complex-state if the presence of ICs represents a physiologic state, or an immune complex-disease if ICs occur under special circumstances only, such as in the EPH-gestosis syndrome. In both of these instances, the presence of ICs may directly influence the maternal immune system, the fetal immune system, or result in very specific effects on associated immune complex-diseases. These effects and the possible influence of immune complex-diseases on normal pregnancy are extensively discussed. It is concluded that a clear definition of pregnancy as a possible IC-state or IC-disease is required. The confirmation of such a concept will necessitate a review of our clinical management protocols for a number of medical conditions.