BOVINE LEUKOCYTE ADHESION DEFICIENCY - IN-VITRO ASSESSMENT OF NEUTROPHIL FUNCTION AND LEUKOCYTE INTEGRIN EXPRESSION

Bovine leukocyte adhesion deficiency (BLAD) was identified in a two-mo nth-old Holstein heifer calf using DNA-polymerase chain reaction analy sis of the affected calf and other clinical parameters. Neutrophil int egrin expression (CD18, CD11a, CD11c), aggregation, and transendotheli al migration were studied in vitro. Neutrophils were isolated from the affected calf and from normal, healthy, age-matched control Holstein calves. Neutrophils isolated from the affected BEAD calf had decreased expression of leukocyte integrins on their cell surface, decreased ab ility to aggregate in response to chemotactic stimuli, and decreased a bility to migrate across bovine endothelial cell monolayers in vitro. Transendothelial migration of neutrophils from normal calves was reduc ed to levels comparable to the BLAD neutrophils by treatment with an a nti-CD18 monoclonal antibody (MAb 60.3). Peripheral-blood lymphocytes from the BEAD calf also expressed negligible levels of leukocyte integ rins, similar to their neutrophil counterparts. Our experimental findi ngs in vitro correlate well with the clinical observations of decrease d leukocyte trafficking and diminished host defense in leukocyte adhes ion-deficient animals. The syndrome of BLAD may be a suitable model fo r one of the human leukocyte adhesion deficiency disorders.