Cytotoxic antibodies to human leukaemia cells in normal human sera

Antibodies cytotoxic for human leukaemia cells were demonstrated in the serum of normal individuals: two of them being the fathers of leukaemia children, the third one being a normal unrelated donor. One of these sera (obtained from the father of an eight years old girl with acute myeloblastic leukaemia) appears to react widely with cells from acute leukaemias, both lymphoid and myeloid. On the other hand, the serum obtained from the normal blood donor appears to react almost exclusively with cells from acute lymphoblastic leukaemias, and more especially with those which do not form rosettes with sheep red cells.