Anomalous Reactivity of Certain HL-A Typing Sera with Leukemic Lymphocytes

Certain anti-HL–A sera react more frequently with lymphocytes of chronic lymphatic leukmia than with normal lymphocytes. Selected antisera for most but not necessarily all HL–A specificities may show this hyperreactivity. Antisera to the W19 and possibly the HL–A27 complexes seem to be involved more often than are others. CLL lymphocytes can be typed accurately only if a sufficiently large number of antisera of each specificity are employed. Cross-absorption analysis of sera EV, Thorsby-FJH, and THA, using normal and CLL lymphocytes, yields evidence for six or more additional antigenic factors on CLL cells which are not obviously related to the HL–A system. Possible interpretations of these findings involve cross reactions within the HL–A system, reactivity with postulated non-HL–A receptors on cell surfaces, with antigens specific for different varieties or subdivisions of chronic lymphatic leukemia (leukemia type-specific antigens), or with T-cell or B-cell antigen systems that might be more abundantly expressed on leukemic than on normal cells. While a few anti-HL–A sera are shown to have anti-immunoglobulin antibodies, such antibodies do not suffice to explain the anomalous reactions.