IDENTIFICATION OF CD45 (LEUKOCYTE COMMON ANTIGEN) IN THE DOMESTIC CAT

Feline CD45 (leucocyte common antigen, LCA) was characterised by using the mouse monoclonal antibody, WC45a. Its specificity was established on the basis of its reactivity with different lymphoid tissues, as ju dged by flow cytometry and immunohistochemistry, and of the molecular weight of its antigen in different tissues. It reacted with all the le ucocyte populations tested including T and B lymphocytes, granulocytes and monocytes. By immunohistology it reacted only with leucocytes and not with endothelia, epithelia or connective tissue. It precipitated cell surface polypeptides, of M(r) 180,000 to 220,000 from lymph node cells, and therefore apparently recognised an epitope represented on m ost of the isoforms of the CD45 family.