Haemagglutinins produced in vitro by human lymphoblastoid cells

Haemagglutinins in the supernatants of four human lymphoblastoid lines have been partially purified by ammonium sulphate precipitation, centrifugation on a sucrose gradient or passage through a Sephadex G-200 column. Haemagglutinating activity in all cases appears to be associated with a high molecular weight fraction with the characteristics of IgM and activity can be recovered by elution of material adsorbed onto an anti-IgM column. On iso-electric focusing, a very small number of molecular species seems to be involved. It is likely that these lines constitute the first in vitro human systems in which the synthesis of homogenous immunoglobulins with known antibody specificity can be studied.