Human thymocytes secrete luteinizing hormone: an autocrine regulator of T-cell proliferation.

There is evidence that there may be bidirectional communication between immune and gonadotropin producing cells. In the present study we describe the secretion and function of an LH like peptide secreted from the human thymus. Serial dilutions of thymic extracts obtained from surgically removed thymic tissues displaced I125 LH from LH antiserum parallel to that produced by pituitary LH. Thymic LH was detected as early as 10 days of age and maximal concentrations were noted at 5 months. Utilizing a sensitive and specific hormonal enzyme linked immunoplaque assay developed in our laboratory, we were able to detect LH secretion from unstimulated human thymocytes. Neutralizing endogenously released LH in PHA stimulated thymocytes with LH antiserum significantly inhibited thymidine incorporation. We conclude that an LH-like peptide is secreted by human thymocytes which acts as an autocrine co-mitogen in lymphoproliferation.