Precipitation of serum proteins by phytohaemagglutinin.

Phytohaemagglutinin (PHA) produced precipitin lines in agar diffusion tests with all the 506 serum samples obtained from normal Nigerians. A few (3%) of the normal sera reacted weakly; in contrast a good proportion (29%) of the lymphoma and leukaemia sera tested were either negative or poorly reacting. Immunoelectrophoretic analysis showed that PHA reacts with some of the α-, β- and γ- globulins of human and animal sera, and that there were marked species differences in the degree of reactivity of the three classes of proteins. The γ-globulins of normal rabbit serum reacting with PHA were different from the specific antibodies produced in PHA-immunized rabbits. There is evidence resulting from absorption studies that the haemagglutinin, leucoagglutinin and mitogenic factors of PHA have the same electrophoretic mobility, are recognized by the same antibodies, and together constitute the precipitin factor(s) of PHA.