HLA antibodies cytotoxic only for B lymphocytes.

Of 28 unabsorbed sera from polytransfused individuals or multiparous women, which were not cytotoxic for total peripheral blood lymphocytes, 13 were found to react positively against B cell-enriched suspensions. These 13 sera were further characterized after platelet absorption-elution, as well as by pretreatment with turkey anti-human-beta2-microglobulin serum. Different patterns were found: five sera behaved as pure anti-B cell reagents; four seemed to contain different antibody populations, directed against both B cell determinants and HLA-A, -B or -C antigens; four only contained antibodies directed against HLA-A, -B or -C specificities. Absorption experiments with purified T and B lymphocytes, showed that these last sera, although noncytotoxic for T cells, can be absorbed by them. It was concluded that not all sera reacting only with B lymphocytes recognize specifities absent from T cells, and that all sera should be exhaustively absorbed with platelets before being tested as anti-B cell-specific reagents.