Specificities of heterologous antisera against human leukaemia cells. 1. Reactions against leukaemia cells.

Rabbit or goat antisera directed to ALL, CLL, AML and CML cells were investigated in cytotoxicity tests with different leukaemia and normal cells as targets. After absorptions with erythrocytes and spleen cells from allogeneic donors the antisera killed only leukaemia cells. There was no reaction with remission leukocytes or blood leukocytes from normal donors. Anti-ALL-Sera reacted in 35 out of 49 tests with ALL cells from 13 patients. Apparently the ALL antisera which were directed to the T cell subtype of ALL preferentially affected ALL cells of this subtype. Cross reactions with cells from CLL, AML and CML were not found. Anti-CLL-sera reacted in 10 out of 12 tests with CLL cells from 4 donors, and in 4 out of 20 tests with ALL cells from 7 donors and also with the cells of a CML patient. AML cells from two patients were not killed. Antisera against AML and CML showed extensive cross reactions with cells of myelocytic and lymphocytic leukaemias. Absorption tests demonstrated the presence of two antibody specificities in AML antisera, one of which being directed to a common antigen of AML and ALL cells and another against an antigen of myelocytic leukaemia cells.