Lymphocyte proliferative response in vitro and its cellular dependency in guinea-pigs with experimental allergic orchitis.

The development of cellular hypersensitivity was measured by the proliferative response of lymph node cells in vitro and a skin test to partly purified testicular antigen. There was a slight stimulation of lymph node cells and of the delayed cutaneous response at 1-2 weeks after sensitization with testicular antigen in Freund's complete adjuvant and then, after a decline in response, there was a pronounced peak at 6 weeks after sensitizaton. The early response coincided with the onset and active inflammatory stage of the effect on the testis, while the major peak was consistent with a state of aspermatogenesis. The proliferative response of unseparated lymph node cells could not be attributed to the function of T or B cells acting alone, although at 6 weeks after sensitization B-cell populations did become slightly responsive to antigen. The response of T lymphocytes was enhanced by the presence of B lymphocytes or peritoneal macrophages at 2 and 6 weeks after sensitization, but B cells did not appear to interact with macrophages. We conclude that T cells are essential to the proliferative response of lymph node cells during the induction of experimental allergic orchitis in guinea-pigs.