Functional nerve growth factor receptors on human B lymphocytes: Interaction with IL-2

In addition to its neurotrophic activity, nerve growth factor (NGF) has been shown to interact with cells of the immune system. We have characterized the effects of NGF on human B cell proliferation and the regulation of NGF receptor expression on these cells. Nerve growth factor receptors were expressed on all tonsillar and peripheral blood B cells and this expression was increased upon activation of the cells. NGF augmented the mitogenic effect of the T-independent B cell mitogen, Staphylococcus aureus Cowan I strain, and provided a progression signal to competent B cells. The proliferative response was augmented when the progression signal provided by NGF was combined with that provided by IL-2 but not with IL-4. One effect of the interaction between NGF and IL-2 appears to occur at the receptor level, because each of these ligands increased the expression of the receptor for the other ligand, whereas IL-4 was without effect. These results demonstrate the expression of functional receptors on human B lymphocytes, the involvement of NGF in immunoregulation, and indicate that NGF may act as a B cell growth factor.