Natural occurrence of a humoral response to Candida in human amniotic fluid.

With a sensitive indirect immunofluorescent technique, we studied the antibody response to Candida albicans in 150 human amniotic fluid (AF) specimens at 15 to 18 weeks' gestation. Specific IgG was detected in 94.7% of the samples and specific IgA, in 98%, while 1.3% were negative in both tests. A comparison of the mean ratio of anticandidal titers (IgA/IgG) in AF and human serum indicated a predominance of IgA activity in AF and the reverse in serum (2.01 versus 0.66, p less than 0.001). There was no correlation between IgG and corresponding IgA titers, which supports the fetal origin of IgA. Humoral immunity alone had no discernible influence on the growth of C. albicans in midtrimester AF. It is suggested that the synthesis of specific IgA is genetically determined because it presumably offers some functional advantage over transmitted maternal IgG in the local defensive mechanisms of the amniotic cavity.