[Immunoglobulins and antibody titre in amniotic fluid of Rh-isoimmunized pregnant women (author's transl)].

On 90 samples of amniotic fluid coming from 54 cases of Rh-isoimmunization submitted to amniocentesis one or more times, the following tests were done: 1.) Coombs indirect test; 2) immunoelectrophoresis; 3) quantitative determination of immunoglobulins. The results were related to the degree of immunization as determined by Coombs indirect test on the mothers' serum and spectrophotometric curve of the amniotic fluid. For reasons of comparison, quantitative determination of immunoglobulins were performed on samples of amniotic fluid from 39 pregnant non-immunized patients. It was found that there was a direct relationship between antibody titers in the mothers' serum and those in the amniotic fluid, with the latter values always being inferior. Moreover, it was found that the level of IgG in the amniotic fluid and the degree of maternal immunization were proportional, with higher titers in the more severe cases. In addition to the routine tests, the determination of anti-Rh antibodies and titers of IgG in amniotic fluid can be useful in further evaluating degree of immunization in Rh-incompatibility. Furthermore, small quantities of IgA were found in amniotic fluid: these IgA were probably of secretory type (SIgA) and of amniotic origin, and therefore independent of any active immunization. Finally, all determinations of IgM were negative.