EXPRESSION OF BETA-2 INTEGRINS ON BLOOD LEUKOCYTES OF COWS WITH OR WITHOUT BOVINE LEUKOCYTE ADHESION DEFICIENCY

Peripheral blood leukocytes of 11 normal cows, 7 cows heterozygous and 2 heifers homozygous for bovine leukocyte adhesion deficiency (BLAD) were analysed by now cytometry for the intensity of their beta 2 integ rin expression (LFA-1(CD11a/CD18), CR3 (CD11b/CD18) and CR4 (CD11c/CD1 8)). BLAD-homozygotes revealed no or a very weak expression of the bet a 2 integrins and had a 10-fold and 4- to 5-fold increase in absolute number of neutrophils and monocytes, respectively, whereas the absolut e number of lymphocytes remained normal. The mean fluorescence intensi ty (MFI) of the beta 2 integrins (CD18) in heterozygous animals nas 56 to 90% of this in the normal cows (MFI between 14 and 512). The diffe rence in the expression level was most pronounced for LFA-1 on the sma ll cluster of lymphocytes with the highest MFI for LFA-1. Repeated ana lysis and phorbol myristate acetate stimulation revealed that the LFA- 1 expression on this high-expressing cell population of the peripheral blood allowed a ready identification of BLAD-heterozygotes by flow cy tometry. (C) 1997 Elsevier Science B.V.