Fetal inflammatory response in second trimester candidal chorioamnionitis

Candidal chorioamnionitis is an uncommon and apparently rather indolent intrauterine infection in which the fetus is able to marshal some of the immunological forces at its disposal against an easily visualized antigen impinging on lung mucosal surfaces. In a retrospective histological study of one of the largest reported series of these cases, we have encountered one each of 13, 16 and 22 weeks gestation, respectively. Of these, the youngest at 13 weeks showed no inflammatory response or positive cells on immunoperoxidase staining for immunoglobulins and proliferating Candida colonies were evident in the lungs. The 16 and 22 week cases revealed a unique giant cell response in the terminal airways and increasing numbers of cells staining positively for immunoglobulins, predominantly IgM, but with an increased proportion of IgA positive cells in the older case. Preliminary studies with a pan-T-cell antiserum on paraffin-embedded lung tissue from these cases have been encouraging with few positive cells seen in sections from the 13-week or control cases but abundant cells in the lungs of the two older infected cases. Some aspects of the relationship of these uncommonly encountered cases to the ontogeny of human immunity are discussed.