Human B-lymphocyte maturation sequence revealed by TPA-induced differentiation of leukaemic cells.

Normal human B cells and leukaemic B-cell populations in common-type CLL undergo sequential shifts in proportions of the three B-cell subsets, defined by expression of mouse erythrocyte receptors R1 and R2, during TPA-induced differentiation to plasmacytoid cells in vitro, suggesting that the B-cell differentiation pathway is R1 +R2+ leads to R1 -R2+ leads to R1 -R2- leads to immature plasmacyte. Maturation of the less common type of CLL with a predominance of R1 -R2+ type cell was in agreement with this model. Changes in Fc gamma, Fc mu and C' receptors were also observed during maturation. A model of human B-cell maturation is presented on which common sites of blockage in leukaemia can be located.