• Contact sensitivity;
  • cyclophosphamide;
  • humoral response;
  • testicular macrophages;
  • transforming growth factor-β

Problem:  Testicular macrophages (TMf) participate together with Sertoli cells in formation of blood–testis barrier. The present experiments were aimed to test their immunoregulatory functions in vivo and in vitro.

Method of study:  TMf were purified by glass adherence, rosetting with opsonized erythrocytes and fractionation on discontinuous Percoll gradient (over 95% purity). Their antigen-presenting capacity in humoral and cell-mediated responses was tested in vitro (Mishell–Dutton cultures, proliferation assay) and in vivo (induction of contact sensitivity reaction).

Results:  TMf represent a heterogeneous cell population. Heavier Percoll fractions produce little transforming growth factor (TGF)-β and are efficient antigen-presenting cells in humoral and cell-mediated immune responses. Lighter fractions produce high amounts of TGF-β and are rather tolerogenic than immunogenic. Their immunosuppressive activity can be prevented by treatment of TMf donors with cyclophosphamide or in vitro by anti-TGF-β monoclonal antibody. In non-separated TMf population the immunosuppressive activity prevails.

Conclusions:  Subpopulation of TMf able to trigger specific immune responses is present in the testis but remains under control of other TMf subpopulation which minimizes the risk of development of autoimmune reactions.