Previous studies demonstrated that experimental autoimmune
orchitis (EAO) was produced in C3H/He mice with very high incidence by two or three
subcutaneous injections of viable syngeneic testicular germ cells, without the use of any adjuvants or
immunopotentiators and that the disease induced was characterized by a complete lack of
epididymitis despite a definite
orchitis with
hypospermatogenesis. In this report, immunohistochemical characterization of immune cells in the fully-developed orchitic lesion was carried out using
monoclonal antibodies and immunoperoxidase staining. Thy-1.2+ cells, Mac-1+ cells, B220+ cells and cytoplasmic Ig-bearing cells in the lesion were estimated to be approximately 30, 15, 20 and 30% of all inflammatory cells, respectively. Major phenotype of T cells in the lesion was CD4+ (approximately 85%) with the remainder (approximately 15%) being CD8+. The percentages of cytoplasmic
IgG-,
IgA- and
IgM-bearing cells were estimated as approximately 35, 60 and 5% of all cytoplasmic Ig-bearing cells, respectively. Deposits of
immunoglobulins and third component of
complement were identified on the basement membrane of the seminiferous tubules, interstitium between the tubules, vessel endothelium and degenerated germ cells in the lesion. Circulating
antibodies directed against the acrosomal portion of germ cells were detected in
IgG and
IgM classes but not in
IgA class. Inflammatory cells (including macrophages, B cells and, probably, activated T cells) in the lesion were Ia+, but Leydig cells, Sertoli cells and germ cells did not
stain for Ia at all.