The influence of Rh hapten therapy on the course of Rh isosensitization in pregnancy.

By CARROLL L. SPURLING, M.D. , MILTON S. SACKS, M.D. , AND ELSA F. JAHN, B.S. W ITH clarification of the pathogenesis of erythroblastosis fetalis it became evident that ideal therapy should be directed either at preventing the formation of maternal Rh antibodies, or, if already present, their passage into the fetal circulation in harmful amounts. Early therapeutic attempts with these goals in mind, using vitamin C,’ serum containing blocking antibodies,2 injections of Rh-positive blood,3 typhoid vaccine,4 and ethylene disulfonate5 were uniformly unsuccessful. The possibility that a specific Rh hapten derived from Rh-positive red blood cells might be effective in neutralizing Rh antibodies was first suggested by Belkin and Wiener in 1944.#{176} Interest in the subject was renewed two years later by Calvin, Evans, Behrendt, and Calvin,7 who isolated by physical methods a lipoprotein substance from Rh-positive red cells which was shown specifically to inhibit Rh antisera in vitro. In 1947, Carter5 prepared an ethereal extract from laked alcohol-precipitated Rh-positive cells, lipid in nature and nonantigenic, which was also said to inhibit hemagglutination by Rh antisera and to fix complement. The material was thought to represent Rh hapten in an impure form and to be essentially the same as that described by Calvin et al. in protein combination. Preliminary reports of clinical trials with the latter material by Loughrey and Carter,9 Carter,1#{176}and more recently by Goldsmith” seemed to indicate that it was effective in reducing maternal Rh antibody titers and in the treatment of erythroblastotic infants. On the other hand, I sensitized women treated with Rh hapten by Unger’2 failed to show any immunologic response to the material. The purpose of the present communication is to report in detail the results obtained in the treatment of io Rh-negative sensitized pregnant women with Rh hapten.