Expression of adhesion structures during B cell development in man

We have used three-color flow cytometry to study the expression of adhesion structures during B cell development in man. The results indicate that the cell-surface molecule(s) recognized by 515, a mAb which defines a broadly expressed family of cell-surface glycoproteins that includes lymphocyte homing receptors, exhibit a clear bimodal distribution (515(lo) and 515(hi)); 515(hi) cells were found exclusively on more mature B cells which already expressed high levels of CD20. Earlier, less mature B cells, identified by their expression of CD10, were uniformly 515(lo). In contrast, the CD11a/LFA-1 Ag was acquired gradually over the course of B cell development. B cells which expressed high levels of CD20 expressed three to six times as much CD11a/LFA-1 as cells which expressed CD10. Interestingly, expression of the 515(hi) phenotype was tightly correlated with that of Leu-8, a marker previously shown to define maturational and function subsets of B cells. These data document the coordinated regulation of multiple cell surface structures during B cell ontogeny, and demonstrate that adhesion structures necessary for proper B cell function are precisely up-regulated during B cell differentiation in man.