Immunopathology of in situ seminoma

In this study of the seminomatous human testis the composition, activity an d apoptosis of lymphocytes infiltrating the immune-privileged seminiferous tubules with in situ seminoma were studied by immunohistochemistry and DNA fragmentation detection. Likewise the lymphocytes infiltrating the invasive seminomas were studied. The study showed equal numbers of CD4+ and CD8+ T cells and B cells, about 30% of the cells. Very few T gamma/delta and NK ce lls were present. The activity in terms of IL-2-R, FasL and perforin expres sion was low. Apoptosis of the lymphocytic cells was limited. No difference s were observed between the lymphocytes in seminiferous tubules with in sit u seminoma and the lymphocytes in invasive tumours. The study suggests that either specifically committed lymphocytes are not present or, if present, immune-suppressing mechanisms in addition to FasL may be working.