T cell clones with normal or defective O-galactosylation from a patient with permanent mixed-field polyagglutinability

Abstract

To delineate the extent of O-galactosyltransferase deficiency within the lymphoid lineage, monoclonal antibody specific for the Thomsen-Friedenreich (TF) antigen (Gal beta 1----3GalNAc alpha 1-O-Ser/Thr) and its precursor the Tn antigen (GalNAc alpha 1-O-Ser/Thr) were applied to the flow cytometric analysis of peripheral blood lymphocytes from a patient with permanent mixed-field polyagglutinability (PMFP). We show that only a minor population of 4% expressed the Tn antigen which is in contrast to 93% of the patient's erythrocytes carrying the defect. Tn+ lymphocytes mainly belonged to the CD3+ subset, but were also CD19+ or CD16+. Both Tn+ and TF+ T cell clones from patient R. R. were established and shown to belong to the CD4+ or CD8+ antigenic subset. Three glycosyltransferase activities were determined in lysates from these clones: all Tn+ clones were deficient in UDP-Gal: GalNAc alpha 1-O-Ser/Thr beta 1----3 galactosyltransferase (beta 3Gal-T) activity; by contrast this activity was present in all lysates from TF-expressing clones. UDP-GalNAc: polypeptide alpha-N-acetylgalactosaminyltransferase (GalNAc-T) and UDP-Gal: GlcNAc-R beta 1----4 galactosyl-transferase (beta 4Gal-T) exhibited similar activities in both Tn+ and TF+ T cell clones. As a consequence of defective O-galactosylation in Tn+ T cells, cell surface sialic acid of Tn+ clones was reduced by greater than 50% when compared to TF+ clones as demonstrated by sialic acid-specific labeling using fluoresceinated Limax flavus agglutinin(LA) and flow cytometry. The Tn phenotype of T cell clones was stable for more than 1 year of continuous expansion in vitro. These data demonstrate that in PMFP, T cells may also be affected by the O-galactosyltransferase deficiency which is accompanied by a substantial loss of cell surface sialic acid. However, the frequency of Tn+ lymphocytes in peripheral blood from patient R.R. was strikingly low. These T cell clones should be useful to study the defect at a genetic level and the importance of O-linked carbohydrates for proper T cell function.