Immunophenotype of vessel wall infiltrate.

Sections of testes containing vessels infiltrated with mononuclear cells were stained with monoclonal antibodies to CD20 (panel A), a B-cell marker; CD45R0 (panel B), a pan T-cell marker and CD8 (panel C), a cytotoxic T lymphocyte marker. The primary antibodies were then labeled with horseradish peroxidase–conjugated antibody and reacted with color substrate. Note the absence of CD20 (panel A) staining and the large proportion of mononuclear cells staining brown indicating the presence of CD45R0 and CD8 cells.