Antigenic determinants of tubular basement membranes and Bowman's capsule in rats.

Kidney sections from several inbred rat strains were studied with an indirect immunofluorescence technique using five different, selected rat antisera which contained antibodies against the tubular basement membrane (TBM). The sera came from transplanted animals, an apparently normal animal, and animals treated with spleen cells in complete Freund's adjuvant. Upon panel analysis, at least two different antigenic determinants were recognized on the proximal TBM: One was present in nine and one was present in seven of the 15 strains tested; both determinants appear to be expressed in most antigen-positive strains. Using kidneys from major histocompatibility complex (MHC)-congenic strains, it was shown that the TBM antigens are encoded outside the MHC region. Three sera produced variable staining of Bowman's capsule in association with the proximal TBM; two sera produced clearly discordant staining of Bowman's capsule and proximal TBM. The capsular antigens were also coded outside the MHC region. These observations suggested the existence of at least two different antigenic determinants on proximal TBM. Bowman's capsule appeared to have antigenic determinants in common with the proximal TBM as well as distinct determinants.