Human T cell IgD receptors react with O-glycans on both human IgD and IgA1.
Previous studies on murine T cell IgD-R have shown that these receptors recognize N-glycans of murine IgD, and not of other Ig isotypes. We have now studied the specificity of IgD-R on human T cells. Human IgD digested with proteinase K to fragments of < 5 kDa inhibit the ability of T cells to form rosettes with IgD-coated ox erythrocytes. The same amount of digested IgG does not. We tested all the human Ig isotypes: IgG1, -2, -3, -4, IgA2, IgE and IgM fail to inhibit significantly at 20 microg/assay. However, IgA1 is as effective as IgD itself, showing approximately 60 % and 80 % inhibition at 5 microg and 10 microg/assay. Human IgA1 and IgD both contain Gal-1 --> 3-GalNac-rich O-linked glycans, and on this basis are both bound to ricin and jacalin. The O-linked glycans may therefore also represent the common moiety binding to IgD-R. Disaccharides Gal-1 --> 3-GalNac, and Gal-1 --> 4-Glc at 10 microg/assay blocked IgD rosetting while Gal-1 --> 6-Glc did not. We conclude that the human IgD-R is a lectin, differing from the murine IgD-R in that it has both IgA1 and IgD as ligands.
Swenson
C D
CD
Department of Pathology and Kaplan Comprehensive Cancer Center, NYU School of Medicine, New York, NY, USA.
Patel
T
T
Parekh
R B
RB
Tamma
S M
SM
Coico
R F
RF
Thorbecke
G J
GJ
Amin
A R
AR
D000818:Animals; D001665:Binding Sites; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D004187:Disaccharides / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007070:Immunoglobulin A / Q000737:chemistry / Q000378:metabolism*; D007072:Immunoglobulin D / Q000737:chemistry / Q000378:metabolism*; D066298:In Vitro Techniques; D051379:Mice; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D011961:Receptors, Fc / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology*
D004187:Disaccharides; D007070:Immunoglobulin A; D007072:Immunoglobulin D; D011134:Polysaccharides; D011961:Receptors, Fc; C050855:immunoglobulin D receptor