Expression of common acute lymphoblastic leukaemia antigen and terminal deoxynucleotidyl transferase in normal mononuclear blood cells during diffusion chamber culture

Peripheral mononuclear blood cells of 2 healthy individuals were cultured over a 13 d period in diffusion chambers. A high percentage of cALL antigen positive cells and later on TdT containing cells appeared during culture. The cALL+ cells could be clearly distinguished into 2 groups: a population with weak and diffuse fluorescence and a small number of ring-like brightly dyed cells. The first group develops into TdT+ cells and therefore resembles immature T-cells. The interpretation of the ring-like stained cells is still preliminary, but it cannot be excluded, that these cells represent a cell population with more than lymphatic differentiation capacity.