The reactivity of monoclonal antibodies entered in the panels of the Third Workshop on Ruminant Leucocyte Antigens with lymphocytes and monocytes of normal and beta 2-integrin deficient (Bovine Leucocyte Adhesion Deficiency: BLAD) animals was determined by flow cytometry to investigate potential specificities to alpha- or beta-chains of beta 2-integrins. From the 13 monoclonal antibodies that were entered as having specificity for CD11/CD18 antigens, ten were confirmed correct, but three had reactivity with cells from BLAD animals. We conclude that our approach provides an easy way to reliably identify the majority of beta 2-integrin specific monoclonal antibodies.