The β2 or leukointegrin family is comprised of three structurally related leukocyte surface heterodimers: LFA-1 (CD11a/CD18), Mac-1/Mo-1 (CD11b/CD18), and p150,95 (CD11c/CD18). In this work, we describe a novel canine β2 (CD18)-associated leukointegrin, designated αd. Expression of αd in tissues was prominent in macrophages in splenic red pulp, lymph node medullary regions, and bone marrow. In peripheral blood, αd expression was limited to a minor subpopulation of CD8+ T cells, which included small lymphocytes and large granular lymphocytes. A minor subpopulation of either CD8+ or CD4-CD8- splenic red pulp lymphocytes also expressed αd. Immunoprecipitation of αd from canine splenocytes revealed a heterodimer of 155 kDa and 95 kDa. Prior clearance of splenocyte extracts with an anti-CD18 mAb resulted in complete removal of αd. In addition, prior clearance of canine splenocyte extracts with anti-CD11a, anti-CD11b, or anti-CD11c mAb failed to clear αd. These immunoclearance data indicated that canine αd was antigenically distinct from the three known CD11 molecules, and occurred as an αdβ2 heterodimer. Amino acid sequencing of canine αd affinity isolated from spleen further suggested that canine αdβ2 probably represented a fourth member of the canine leukointegrin family via its homology to a subsequently discovered, novel human leukointegrin, αdβ2, which further supported the uniqueness of the canine protein. The discovery of canine αd, and the demonstration of its highly restricted cell and tissue distribution, support a re-evaluation of leukointegrin-dependent inflammatory and immunologic interactions that involve cells now known to express αd.
|Original language||English (US)|
|Number of pages||10|
|Journal||Journal of Immunology|
|State||Published - 1995|
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