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Abstract

We have previously shown that the surface αβ T cell antigen receptor (TCR).CD3 complex borne by human CD4⁺ and CD8⁺ T lymphocytes can be distinguished using mAbs. Using two unrelated sets of antibodies, we have now extended this finding to the surface αβTCR.CD3 of seven additional mammalian species (six non-human primates and the mouse). We have also produced data supporting that differential glycosylation of the two main T cell subsets is involved in the observed TCR.CD3 antibody-binding differences in humans. First, we show differential lectin binding to human CD4⁺ versus CD8⁺ T lymphocytes, particularly with galectin 7. Second, we show that certain lectins can compete differentially with CD3 mAb binding to human primary CD4⁺ and CD8⁺ T lymphocytes. Third, N-glycan disruption using swainsonine was shown to increase mAb binding to the αβTCR.CD3. We conclude that the differential antibody binding to the surface αβTCR.CD3 complex of primary CD4⁺ and CD8⁺ T lymphocytes is phylogenetically conserved and associated with differential glycosylation. The differences may be exploited for therapeutic purposes, such as T cell lineage-specific immunosuppression of graft rejection. Also, the impact of glycosylation on CD3 antibody binding requires a cautious interpretation of CD3 expression levels and T cell numbers in clinical diagnosis.