Molecular cloning and characterization of cDNA encoding CD11b of cattle

Molecular cloning, characterization and gene expression of the full length cDNA encoding the porcine CD11b(αM) and chromosomal localization of the porcine CD11a(αL)-CD11b(αM)-CD11b(αD) gene cluster

CD11b (α(M)) is a cell-surface glycoprotein mainly expressed on myeloid cells, required for important interactions during the immune response and involved in the pathogenesis of several diseases. The full length cDNA encoding porcine CD11b protein has been cloned and sequenced. Pig CD11b cDNA sequence contains an ORF of 3459 nucleotides that encodes a deduced polypeptide of 1152 amino acid residues that share with CD11b from other species: High % amino acid identity, common domains (α-I, Ca(++) binding, MIDAS), N-glycosylation sites, and the seven FG-GAP tandem repeats. Real time quantitative PCR expression analysis revealed that CD11b transcripts were highly expressed in neutrophils, showing a lower expression in spleen. The CD11a-CD11b-CD11c gene cluster locates on the porcine chromosome region SSC3p15-17.

CD11b of Ovis canadensis and Ovis aries: molecular cloning and characterization

Leukotoxin (Lkt) is the primary virulence factor secreted by Mannheimia haemolytica which causes pneumonia in ruminants. Previously, we have shown that CD18, the beta subunit of beta(2) integrins, mediates Lkt-induced cytolysis of ruminant leukocytes. CD18 associates with four distinct alpha subunits giving rise to four beta(2) integrins, CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1), CD11c/CD18 (CR4), and CD11d/CD18. It is not known whether all the beta(2) integrins serve as a receptor for Lkt. Since PMNs are the leukocyte subset that is most susceptible to Lkt, and Mac-1 expression on PMNs exceeds that of other beta(2) integrins, it is of interest to determine whether Mac-1 serves as a receptor for Lkt which necessitates the cloning of CD11b and CD18. In this study, we cloned and sequenced the cDNA encoding CD11b of Ovis canadensis (bighorn sheep) and Ovis aries (domestic sheep). CD11b cDNA is 3455 nucleotides long encoding a polypeptide of 1152 amino acids. CD11b polypeptides from these two species exhibit 99% identity with each other, and 92% with that of cattle, and 70-80% with that of the non-ruminants analyzed.