Constitutively hyposialylated human T-lymphocyte clones in the Tn-syndrome: binding characteristics of plant and animal lectins.
Previously, beta 1,3-galactosyltransferase-deficient (Tn+) and normal (TF+) T-lymphocyte clones have been established from a patient suffering from Tn-syndrome [Thurnher et al. (1992) Eur J Immunol 22: 1835-42]. Tn+ T lymphocytes express only Tn antigen GalNAc alpha 1-O-R) while other O-glycan structures such as sialosyl-Tn (Neu5Ac alpha 2,6GalNAc alpha 1-O-R) or TF (Gal beta 1-3GalNAc alpha 1-O-R) antigens are absent from these cells as shown by flow cytometry using specific mABs for TF and sialosyl-Tn antigen, respectively. Normal T lymphocytes express the TF antigen and derivatives thereof. The surface glycans of Tn+ and TF+ cells were then analysed by flow cytometry using the following sialic acid-binding lectins: Amaranthus caudatus (ACA), Maackia amurensis (MAA), Limax flavus (LFA), Sambucus nigra (SNA) and Triticum vulgare (WGA). Equal and weak binding of MAA and SNA to both TF+ and Tn+ cells was found. WGA, LFA and ACA bound more strongly to TF+ cells than to Tn+ cells. Binding of ACA to TF+ cells was enhanced after sialidase treatment. To investigate the possible biological consequences of hyposialylation, binding of three sialic acid-dependent adhesion molecules to Tn+ and TF+ cells was estimated using radiolabelled Fc-chimeras of sialoadhesin (Sn), myelin-associated glycoprotein (MAG) and CD22. Equal and strong binding of human CD22 to both TF+ and Tn+ cells was found. Whereas binding of Sn and MAG to TF+ cells was strong (100%), binding to Tn+ cells amounted only to 33% (Sn) and 19% (MAG). These results indicate that the in vivo interactions of T lymphocytes in the Tn syndrome with CD22 are not likely to be affected, whereas adhesion mediated by Sn or MAG could be strongly reduced.
Mrkoci
K
K
Institute of Physiology, University of Zürich, Switzerland.
Kelm
S
S
Crocker
P R
PR
Schauer
R
R
Berger
E G
EG
D000818:Animals; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000097:blood*; D002240:Carbohydrate Sequence; D002999:Clone Cells; D006402:Hematologic Diseases / Q000097:blood*; D006801:Humans; D037102:Lectins / Q000378:metabolism*; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D037121:Plant Lectins; D010944:Plants / Q000378:metabolism; D011485:Protein Binding; D013577:Syndrome; D013601:T-Lymphocytes / Q000378:metabolism*
D015295:Antigens, Tumor-Associated, Carbohydrate; D037102:Lectins; D037121:Plant Lectins; C040286:Tn antigen; D019158:N-Acetylneuraminic Acid