CHARACTERIZATION OF A NOVEL LEUKOCYTE ACTIVATION ANTIGEN RECOGNIZED BY THE ANTIBODY CMRF-37

We describe a novel activation antigen recognized by the monoclonal an tibody CMRF-37, which is absent or only weakly expressed on resting ce lls but is rapidly induced on T cells, B cells and monocytes following stimulation. Its kinetics of expression (12-24 h after the addition o f the inductive signal) indicate that it is an early activation antige n. The cellular distribution and expression kinetics of the CMRF-37 an tigen differ from other known activation antigens and as such should b e a useful marker of human leucocyte activation.