Peanut agglutinin lectin immunohistochemical staining of normal and neoplastic canine tissues

Peanut lectin binding sites were demonstrated in normal canine tissues and in 114 canine tumors by avidin biotin complex immunohistochemical staining on unfixed cryostat tissue sections. Peanut agglutinin (PNA) receptors occurred in a variety of normal cells and tissues, including lymphoid follicle center cells; cortical thymocytes; basal cells and the stratum spinosum of stratified squamous epithelium; columnar epithelium of the gastrointestinal tract; parietal cells and chief cells of the stomach; some endothelial cells; myelin; chondrocytes; spermatogenic cells; cells of the adrenal medulla; Bowman's capsule and the distal convoluted tubules of the kidney; prostatic, perianal and endometrial epithelium; and the extracellular matrix of connective tissues. Neoplastic cell staining was sporadic and was most often observed in benign or well-differentiated neoplastic tissues in which the corresponding normal cells also expressed PNA binding sites. However, PNA also bound to some tumor cells in which the analogous normal tissues were unstained, including cells of some fibrosarcomas, rhabdomyosarcomas, hemangiopericytomas and proliferating myoepithelial cells in mixed mammary tumors. Although PNA binding is complex and heterogeneous in canine tissues and does not appear to immunohistochemically detect a moiety associated with neoplastic transformation per se in the majority of canine tumors, the expression of PNA receptors may be associated with neoplastic changes in some mesenchymal cell populations.