ETHNIC-DIFFERENCES IN EXPRESSION OF SUSCEPTIBILITY MARKER(S) IN RHEUMATIC-FEVER RHEUMATIC HEART-DISEASE PATIENTS

The ability of monoclonal antibodies (MAb) against a human B lymphocyt e alloantigen has been suggested to discriminate between rheumatic fev er ''susceptible'' individuals and persons with a lower risk of develo ping RF. However, while such MAb have been reported to identify a majo rity of RF/RHD patients in some populations, a reduced discriminatory ability has been observed in others. Antigenic variation in the RF mar ker(s) may exist among ethnic groups which reduce the discriminatory a bility of these monoclonal antibodies. We developed MAb using B lympho cytes from RF patients of North Indian ethnic origin. In this same pop ulation we compared the new MAb (PGI/MN II) with a previously describe d MAb of Caucasian ethnic origin (D8/17). In three groups: acute rheum atic fever patients (no evidence of previous attacks of rheumatic feve r), patients with chronic rheumatic heart disease and normal controls from the same population, we found a greater discriminating ability of PGI/MNII MAb to identify Indian RF/RHD patients than with the D8/17 M Ab. Further, sixty percent of 142 siblings of the RF/RHD patients were ''positive'' when tested with PGI/MN II. The data from these studies suggest that before such MAb can be used for identification of RF ''su sceptibles'' in public health programs, variation among ethnic populat ions must be assessed. (C) 1998 Elsevier Science Ireland Ltd.