The B-cell adhesion molecule CD22 is cross-species reactive and recognizes distinct sialoglycoproteins on different functional T-cell sub-populations.
CD22 is a B cell lineage restricted cell-surface adhesion glycoprotein which recognizes ligands on human T and B cells and cell lines. A soluble recombinant form of human CD22 (hCD22Rg) has been used to identify and characterize CD22-specific ligands on human T cells, one of which has been shown to be the receptor-linked phosphotyrosine phosphatase CD45. Because CD45 plays a pivotal role in lymphocyte activation, we assessed whether human CD22 might display cross-species reactivity with CD45. In the study presented here we demonstrate that human CD22Rg recognizes several murine cell-surface sialoglycoproteins, including CD45, containing sialic acid in alpha 2,6 linkage. Furthermore, hCD22Rg recognizes different ligands on functionally distinct T helper-cell subpopulations and selectively binds medullary thymocytes in vivo. Our results confirm and extend previous observations that CD22 is a sialic acid-binding lectin which interacts with CD45 and other glycoproteins capable of presenting alpha 2,6-linked sialic acid in a manner that promotes high affinity binding. The cross-species reactivity of CD22 with its ligands underscores the potential physiologic importance of CD22-mediated lymphocyte interactions.
Sgroi
D
D
Department of Pathology, Massachusetts General Hospital, Charlestown.
Stamenkovic
I
I
D000818:Animals; D015703:Antigens, CD / Q000276:immunology*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology*; D015815:Cell Adhesion Molecules / Q000276:immunology*; D002460:Cell Line; D006801:Humans; D037102:Lectins; D017493:Leukocyte Common Antigens / Q000276:immunology; D051379:Mice; D011233:Precipitin Tests; D011993:Recombinant Fusion Proteins; D051918:Sialic Acid Binding Ig-like Lectin 2; D012795:Sialoglycoproteins / Q000276:immunology*; D013045:Species Specificity; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; C497867:CD22 protein, human; C497868:Cd22 protein, mouse; D015815:Cell Adhesion Molecules; D037102:Lectins; D011993:Recombinant Fusion Proteins; D051918:Sialic Acid Binding Ig-like Lectin 2; D012795:Sialoglycoproteins; D017493:Leukocyte Common Antigens