The Superoxide-generating System and its Function in Human B Lymphocytes

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We have shown that human peripheral B lymphocytes contain cytochrome b558 (gp91-, and p22-phox) and cytosolic proteins, p47-and p67-phox, all are known to be essential for the superoxide generation. The amounts of these components in B lymphocytes were much lower than than those in neutrophils, which may reflect the weak superoxide-generating activity of B lymphocytes. Mean amounts (n=8) of gp91-, p22-, p47-and p67-phox in peripheral B lymphocytes as calculated from intensity of the blots were 1.1%, 2.6%, 17.9%and3.9%, relative to those in neutrophils on the basis of cell number. Epstein-Barr virus (EBV) -transformed cell lines derived from normal B lymphocytes also possessed cytochrome b558 and two cytosolic proteins.Based on our observation that EBV-tranaformed B cell lines derived from CGD patients did not show the activity, in contrast to those obtained from normal individuals we concluded that generation of the superoxide anion by B cell lines was due to the presence of the same system as that in phagocytes. Based on our observation that EBV-transformed B cell lines derived from CGD patients did not show the activity, in contrast to those obtained from normal individuals.Since cross-linking of surface immunoglobulins activates the superoxide-generating system in B lymphocytes, it is expected that the superoxide anion is released when the cells are exposed to a specific antigen or when the cells interact antigen-dependently with T lymphocytes. In the latter case, cross-linking of HLA-DR on the B lymphocytes may also take place. It is possible, therefore, that generated superoxide anion modulates immune responses either by affecting antigen-processing or by promoting growth of T lymphocytes. Further studies are needed to elucidate its role.