Lacrimal gland-derived lymphocyte proliferation potentiating factor

Purpose. To determine whether lacrimal gland acinar cells are involved in modulating local immune response; to isolate and characterize a lacrimal gland factor that exerts biological activities on T lymphocytes. Methods. A protein factor has been purified from lacrimal gland extracts by a combination of ion exchange and gel-filtration chromatography. This factor has the capacity to enhance proliferation of T lymphocytes upon stimulation with a mitogen or an antigen. We have, therefore, called this substance lacrimal gland-derived lymphocyte proliferation potentiating factor (LG-F). Results. Lacrimal gland-derived lymphocyte proliferation potentiating factor has a molecular weight of approximately 65,000 daltons as determined by gel- filtration and by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. T cells demonstrate greater proliferation when cultured with high concentrations of concanavalin A (Con A) in the presence of LG-F, as compared with culture without addition of LG-F. This enhancing effect of LG-F may be mediated by IL-2, because the final cell count correlates with the levels of IL-2 secreted by LG-F-activated cells. Lacrimal gland-derived lymphocyte proliferation potentiating factor is nonmitogenic for T cells, but its potentiating effect is antigen-dependent. Dual stimulation of OA-primed T cells with both OA and LG-F results in greater proliferative activity, in contrast to culture with OA alone. Conclusions. The results suggest that lacrimal gland cells may interact with the immune system by elaborating nonspecific factors that modulate lymphocyte proliferation and augment lymphokine production. The presence of such a factor in the lacrimal gland may prove to be of importance in the generation of local immune responses.