Time-course expression of polypeptides carrying blood group antigens during human erythroid differentiation

The time course expression of blood group antigens was examined by now cytometry using a two-phase liquid culture system that supports the proliferation and maturation of human erythroid progenitors from adult peripheral blood. The progression towards erythroid differentiation was followed by the expression changes of the transferrin receptor (CD71(++)) and glycophorin A (GPA(+)). Pour main categories of blood group markers were identified: (i) those characterized by an early expression like ABO (A), Kell (K:2) and Rh50 which were detected in the Epo-independent phase 1, (ii) those including GPC (Gerbich, Ge antigens) and Fy6 which were expressed in the late phase 1, (iii) GPA (MN antigens), Wr(b) (Band 3/GPA interaction), Rh(D, Cc/Ee) and LW which appeared during the Epo-dependent phase 2 and (iv) those like Jk(3) and Lu-b which were expressed in late phase 2, Regarding blood group molecules exhibiting adhesive properties (LW/ICAM-4, Ok(a) and Lu) the most significant event was a sharp decrease of Ok(a) (neurothelin) expression with the concomitant loss of ICAMs expression during the later stage of differentiation. These studies suggest that Ok(a), ICAMs and LW might contribute to the adhesive interactions involved in the formation of erythroblastic islands and attachment to stroma cells and the extracellular matrix. We also noted an asynchronous expression of the proteins that compose the core of the Rh complex, since Rh50 glycoprotein was expressed earlier than Rh(D, CE) proteins.