AVIAN LEUKOCYTE COMMON ANTIGENS - MOLECULAR-WEIGHT DETERMINATION AND FLOW CYTOMETRIC ANALYSIS USING NEW MONOCLONAL-ANTIBODIES

New leucocyte common antigens expressed on all the normal chicken leucocytes have been characterized using two monoclonal antibodies designated as K-11 and K-55. These monoclonal antibodies stained virtually 100% of the leucocytes derived from various lymphoid organs including the spleen, thymus, bursa of Fabricius, caecal tonsil and peripheral blood, as well as a monocytic cell line (MC29), a B cell line (LSCC-RP9), and a T cell line (CU 12). However, they did not stain mature erythrocytes, intestinal epithelial cells, or chicken embryonic fibroblasts. The two monoclonal antibodies showed different staining patterns and detected non-overlapping epitopes on MC29 cells in two color immunofluorescence analysis. Western blot analysis under non-reducing conditions showed that the monoclonal antibody K-11 recognized three splenic leucocyte proteins with molecular weights of 92, 42 and 41 kDa, whereas the monoclonal antibody K-55 recognized two proteins with molecular weights of 97 and 42 kDa. The data indicate that the monoclonal antibodies K-11 and K-55 recognize novel leucocyte-common antigens which have lower molecular weights than the previously reported leucocyte-common antigen family.