Characterization of the Superoxide-Generating System in Human Peripheral Lymphocytes and Lymphoid Cell Lines

抄録

In B lymphocytes, but not T lymphocytes, isolated from human peripheral blood, we detected the four protein components essential for “the respiratory burst” by immunoblot analyses using peptide-directed antibodies. These are two membrane proteins, namely, 91-and 22-kDa subunits of cytochrome b₅₅₈, and two cytosolic proteins with molecular masses of 47 and 65 kDa. Like in neutrophils, cytochrome b₅₅₈ was expressed on the cell surface of peripheral B lymphocytes. Mean amounts (n=8) of the 91-, 22-, 47-, and 65-kDa proteins, respectively, in peripheral B lymphocytes calculated from intensity of the blots were 0.011±0.003, 0.026±0.006, 0.179±0.022, and 0.039±0.013 relative to those in neutrophils on the basis of cell number. Epstein-Barr virus (EBV)-transformed cell lines derived from normal B lymphocytes and some B cell lines also possessed cytochrome b₅₅₈ and two cytosolic proteins. Isolated human peripheral B lymphocytes generated the superoxide anion upon cross-linking of surface antigens such as IgM, IgD, IgG, HLA-DR, and CD19. EBV-transformants derived from normal peripheral B lymphocytes and B lymphoid cell lines also generated the superoxide anion when stimulated with various antibodies against surface antigens. These results indicate that peripheral B lymphocytes have substantial amounts of a superoxide-generating system identical to that in phagocytes and that the system is stimulated to generate the superoxide anion by the cross-linking of clonally expressed surface immunoglobulins or of certain surface antigens.