Pathobiology of bovine leukocyte adhesion deficiency in Holstein cattle and its DNA-diagnosis.

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Studies on bovine leukocyte adhesion deficiency (BLAD) in Holstein cattle were performed and results were summarized as follows :1.Analysis of neutrophil function-Neutrophils from affected cattle had function defect, characterized by severely decreased adherence, chemotactic movements, phagocytosis, luminol-dependent chemiluminescent response, and O_2-producing activities. Deficient CD18 expression on neutrophils was clearly detected by flow cytometry. In vitro leukocyte functional abnormalities were associated with impaired CD18.2.Analysis of mononuclear cells-Deficient CD18 expression on mononuclear cells from cattle with BLAD was clearly detected. There were no significant differences in the population of PNA-positive, SIg-bearing lymphocytes and lymphocyte blastogenesis from control and cattle with BLAD.3.Analysis of neutrophils from bone marrow-The number of nucleated cells was 2.9 to 8.8 times higher and the myeloid to erythroid ratio of bone marrow from cattle with BLAD ranged from 2.4 to 12. Activities of chemotactic movements and phagocytosis of neutrophils isolated from bone marrow of cattle with BLAD were documented to be severely impaired.4.DNA-PCR analysis-DNA-PCR method for homolzygous and heterolozygous BLAD was applied to leukocytes from BLAD-affected cattle and 260 Holstein dairy cattle. Mean 10% (26/260) of Holstein dairy cows was proved to be BLAD-carrier, and age was ranged from 2 to 10 years old.These results demonstrate that characteristic of BLAD is closely associated with impaired CD18 expression on leukocytes, and the gene of BLAD-carrier is widely distributed in Holstein populations. This study provide a valuable information for the control of BLAD in Holstein cattle.