JAL (RH48) blood group antigen: serologic observations.

Background: JAL (RH48) is a low-prevalence antigen in the Rh blood group system and anti-JAL has caused hemolytic disease of the newborn. JAL is associated with either a haplotype carrying depressed C and e antigens or one carrying depressed c and e antigens. Blood samples from JAL+ people were tested, published serologic findings were confirmed, serologic studies were extended to include expression of other Rh antigens, and the antibody specificities produced by three sensitized JAL+ probands are reported.

Study Design And Methods: Red blood cell (RBC) samples from 17 (12 probands) JAL+ persons were tested by hemagglutination using standard methods.

Results: RBCs from both the Caucasian JAL+ probands had the (C)(e) haplotype and weakened C, e, hr(B), and hr(S) antigens. JAL+ samples from black persons had the (c)(e) haplotype and expressed weakened c, e, f, V, VS, hr(B), and hr(S) antigens. Plasma from three sensitized c+e+ JAL+ probands contained alloanti-c, alloanti-e, or alloantibody of apparent anti-Rh17 specificity. This study shows that this alloanti-Rh17-like antibody recognizes the high-prevalence antigen antithetical to JAL that has been named CEST.

Conclusions: The presence of the JAL antigen has a quantitative (weakening) effect on the expression of C, e, hr(B), and hr(S) antigens in Caucasian persons and of c, e, f, V, VS, hr(B), and hr(S) antigens in people of black African ancestry. A qualitative effect also was demonstrated by the presence of alloanti-c or alloanti-e in the plasma of two transfused c+e+ patients and by an antibody (anti-CEST) that recognizes the high-prevalence antigen antithetical to JAL.