Faculty Bibliography

Complement-receptor lymphocytes have generally been considered to be a subpopulation of bone-marrow derived (B) lymphocytes. However, the present studies show that essentially all cells with integral surface immunoglobulin from normal human peripheral blood bear receptors for the third component of complement. Moreover, after removal of phagocytes, all cells with complement receptors bear surface Ig. Thus, circulating B cells and complement-receptor lymphocytes are the same population

A subpopulation of cells in murine mesenteric lymph nodes, about 15% of those synthesizing DNA at any given time, homes specifically to the gut and mesenteric nodes of syngeneic recipients within 1 day of i.v. transfer. In contrast, cells from Oeyer's patches or peripheral lymph nodes do not. A large proportion of the B blasts which home to the small intestine has surface Ig, but lacks complement receptors. Thy-1-positive T blasts home to the gut to a lesser extent than B blasts. However, it is probable that equal fractions of B and T blasts home to mesenteric nodes. Homing is not affected by measures calculated to interfere with the combination of cell surface IgA and secretory component

An Ig molecule containing L chains and H chains similar to human delta-chains has been detected on the surface of radioiodinated murine lymphoid cells. Newborn mice have only IgM on their splenocytes. Between 10 and 15 days, the IgD-like molecule appears and increases in amount until 3 mo of age, when it is the predominant cell surface Ig in terms of radioactivity. IgD is found only in peripheral lymphoid tissues and is present in larger amounts on peripheral lymph node cells (approximately 85% of surface Ig) than on splenocytes (approximately 50%). IgD is also present in comparable amounts on cells from both nu/nu and germfree mice, indicating that its expression may be independent of both thymic influence and antigenic stimulation. These studies suggest that there is a switch from cell surface IgM to IgD that occurs during differentiation of virgin B lymphocytes in the spleen