Antigenicity of basement membrane fractions obtained from rat seminiferous tubules

A noncollagenous fraction of basement membrane (D-STBM) obtained from rat testes was submitted to sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis (SDS-PAGE), and eight well-defined bands were detected. A cross-reaction with an antiserum against laminin was revealed by immunoblotting in five bands, with molecular weights ranging from 54 to 64 kDa. No further resolution of these components could be obtained by size exclusion and ionic exchange chromatography. Fifty-two percent of the rats immunized with D-STBM and adjuvants developed a mild multifocal damage of the testis. The lesions were characterized by foci of seminiferous tubules with different degrees of sloughing and/or atrophy of the germinal epithelium. Giant multinucleated cells were frequently seen, and mild interstitial mononuclear cell infiltrates were also detected. By immunofluorescence, deposits of rat IgG with a faint discontinuous linear pattern were observed along the walls of the seminiferous tubules. Circulating antibodies to D-STBM were detected by ELISA in 100% of the rats, whereas in a cross-reaction with laminin antibodies were detected in only 63%. All rats studied revealed a positive delayed type of hypersensitivity (DTH) response to D-STBM. None of the control rats injected with saline and adjuvants presented circulating antibodies to D-STBM or laminin or a positive DTH reaction to D-STBM. Some control group rats (10%) revealed few isolated seminiferous tubules with some degree of sloughing of the germinal epithelium.