THE MONOCYTE MONOLAYER ASSAY - A NONINVASIVE TECHNIQUE FOR PREDICTINGTHE SEVERITY OF IN-UTERO HEMOLYSIS

To test the noninvasive monocyte monolayer assay in predicting hemolyt ic severity in utero, we studied 18 patients from two institutions wit h significant erythrocyte alloantibodies. Serum samples were obtained from each patient. Each subject donated a serum sample during her preg nancy. Monocytes were harvested from a single healthy donor and grown in monolayer culture. Erythrocytes with the appropriate antigens were sensitized with maternal serum and incubated with the monocyte monolay ers. Erythrophagocytosis was scored as a percentage of the positive co ntrol. Perinatal outcomes were assessed post hoc and cases were classi fied as unaffected or mildly, moderately, or severely affected using s tandard definitions. Prenatal management was conducted without knowled ge of the results. Six of the 18 patients had severe disease and one o f the 18 had moderately severe disease. At a cutoff level of 20, the a ssay generated the following results: sensitivity was 7 of 7 (100%), s pecificity was 10 of 11 (90.9%), positive predictive value was 7 of 8 (87.5%), and negative predictive value was 10 of 10 (100%). The monocy te monolayer assay appears to be a useful, noninvasive modality for pr edicting the severity of hemolytic disease in utero.