Autoimmune antibodies in chronic lymphatic leukaemia.

In chronic lymphocytic leukaemia a factor in patients' serum enhances the in vitro viability of the abnormal cells and this has been identified as an antibody. The activity of this factor can be removed by interaction with anti-immunoglobulin and by ammonium sulphate precipitation with a degree of saturation in excess of 46%. Cohn fractionation and chromatography with A-50 Sephadex show that the factor is not a complex but an immunoglobulin. No activity is removed after reaction of sera with 2-mercapto-ethanol and di-thiothreitol. The evidence therefore suggests that a gamma-G immunoglobulin is involved. Concentrated washings from the leukaemic cells behave in exactly the same way as patients' sera and activity is retained in the same fraction during precipitation and purification procedure. The extensive cross-reactivity of the sera suggests a common chronic lymphatic leukaemic antibody and it is considered that an active autoimmune response may be an integral part of the disease.