Evidence that FMC7 is a human B cell differentiation antigen

Abstract

FMC7 is a 105-kDa B cell restricted antigen which is expressed on about 50% of adult human peripheral blood B cells. Seven to ten days following booster immunization with tetanus toxoid, peripheral blood contains a small population of B cell blasts with an increased density of FMC7. The majority of anti-tetanus toxoid antibody secreting cells (both IgM and IgG) are however found in FMC7- B cells. These data indicate that upon in vivo B cell activation FMC7 expression initially increases. B cells involved in antibody secretion have lost the FMC7 determinant.