Observations on the new Rh agglutinin anti-f.

antibodies found in the serum of a hemophiliac who had received numerous blood transfusions. In addition to anti-N, anti-S, and anti-K, the serum contained an antibody which reacted with bloods of certain Rh types, only blood cells from persons bearing at least one chromosome of type cde or cDe being agglutinated by this antibody. It svas postulated that these reactions were due to a new antigen f. It was further suggested that the inheritance of this antigen w'as cie-termined by a pair of allelic genes F and f tightly linked to the familiar Cc, Dd and Ee pairs. In the data of Rosenfield et al., as well as in those of Race and Sanger,2 mdi-viduals who did not have a chromosome bearing the gene combination cc failed to have the f antigen on their cells. Typical examples of the Rh genotypes of persons who lack the f antigen are CDe/CDe, cDE/cDE and CDe/cDE. Persons of the genetic categories CDe/CDe and cDE/cDE are capable of producing anti-c and anti-e respectively. Since such persons lack the f antigen, they are potentially capable of developing anti-f in addition to anti-c or anti-c when immunized with cells from persons w'ith a chromosome of type cDe or cde. The serum of such a person was available in this laboratory and opportunity was t.akeis to test this hypothesis. MATERIALS AND METHODS Dr. Kr., whose blood was of type cDE/cDE, had been deliberately immunized with repeated injections of Rh negative (cde) blood during a five year period. His serum agglutinated saline-suspended Rh negative cells to an end-point of 1:128. It agglutinated all cells containing the antigen e and failed to agglutinate cells lacking this antigen. In order to remove the anti-c, the Kr. serum was subjected to four separate absorptions with equal volumes of washed, packed CDe/CDe cells, each aI)sorption being carried out at 37 C. for 2 hours. To ensure completeness of absorption two further absorptions were made with cells of type CDe/cDE. This serum, when tested against CDe/CDe cells and against CDe/cDE cells by saline, albumin, and indirect Coombs technics, gave negative result.s but was shown to contain a residual antibody which agglutinated saline-suspended Rh negative cells to a titer of 1:32.