Characterization of leukocyte functions from cattle with leukocyte adhesion deficiency (BLAD) and prevalence of BLAD-carrier in Holstein cattle in Japan

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The above-entitled study was performed and the results were summarized as follows :Severe bone resorption, osteolysis and severe progressive periodontitis in submandibula due to dysfunction of leukocytes in heifers with BLAD were demonstrated by radiographic examination. Immunohistochemical analysis of lymph nodes using anti-CD18 antibody demonstrated that CD18-positive cells were not found on those from the BLAD-heifer.Fc receptor expression, cytoplasmic Ca^<2+> signaling, chemiluminescent (CL) response, and electron spin resonance (ESR) combined with spin trapping of blood mononuclear phagocytes from control heifers and a heifer with BLAD were evaluated to elucidate the relationships between complement receptor type 3 (CR3) and Fc receptor expression and their functional responses. Fc receptors on mononuclear phagocytes from the heifer with BLAD were enhanced, and their cytoplasmic Ca^<2+> singnaling, CL responses, and ESR-spin trapping when stimulated with aggregated IgG (Agg-IgG) o … More psonized zymosan (OPZ) appeared to be associated with enhanced Fc receptors.The adhesiveness of control and CD18-deficient bovine neutrophils on culture plates precoated with collagen I,collagen IV,fibronectin and laminin was measured to evaluate the possible factors for adherence to extracellular matrices. The adhesiveness activities of CD18-deficient neutrophils to collagen I,collagen IV and fibronectin were significantly diminished ; however, similar adhesion to laminin was observed in CD18-deficient neutrophils and control neutrophils.Biosynthesis of CD11/CD18 in bovine leukocytes, intracellular Ca^<2+> signaling, CL responses and membrane fluidity of neutrophils from control heifers and a BLAD-heifer were measured. The synthesis of CD11/CD18 complex was clearly detected in leukocytes from a normal heifer, but not in a BLAD-heifer. The ttransient phase of increased Ca^<2+> was clearly detected in neutrophils from a BLAD-heifer stimulated with OPZ,Agg-IgG,whereas the sustained phase was deficient or significantly decreased compared with controls. No differences in membrane fluidity were detected between neutrophils derived from control and BLAD-cattle.Blood samples from 796 Holstein dairy cows in 20 herds from 6 districts in Japan were examined to determine whether they were BLAD-free, BLAD carriers, or BLAD-affected by use of DNA-PCR analysis, BLAD-carrier rates ranged from 0 to 23.5% and the mean BLAD-carrier rate was 8.1% (70/796). Approximately 35% of the dairy herds had a prevalence of more than 10% of BLAD-carriers. The rate of the occurrence of BLAD in Japanese Holstein dairy cattle was estimated to be 0.16% at birth. A program for the eradication of the gene encoding impaired CD18 for BLAD in Holstein cattle is slowly being enacted in Japan.These results demonstrate that pathophysiological changes of BLAD are closely associated with the deficiency of CD18 expression on BLAD-leukocytes. This study provide a valuable information for the control of BLAD in Japanese Holstein cattle. Less