Differential antibody binding to the surface TCR{middle dot}CD3 complex of CD4+ and CD8+ T lymphocytes is conserved in mammals and associated with differential glycosylation

We have previously shown that the surface alphabeta 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 alphabetaTCR.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 alphabetaTCR.CD3. We conclude that the differential antibody binding to the surface alphabetaTCR.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.