LYMPHOCYTES BEARING THE GAMMA/DELTA T-CELL RECEPTORS IN DOWNS-SYNDROME

Subjects with Down's syndrome (DS), or trisomy 21, have an increased susceptibility to infections, malignant diseases and autoimmune phenomena. Various arms of the immune system are severely impaired in trisomic patients. We found that the proportion of blood lymphocytes bearing the gamma/delta T-cell receptor (TCR) was significantly higher in adults with trisomy 21 than in age- and sex-matched healthy controls. Interestingly, the increase was mainly due to an over-expansion of cells which bear non-covalently bound gamma/delta chains on their surface. This contrasts with the normal blood picture, where the great majority of gamma/delta T cells express the disulphide-linked form of the TCR. The fact that trisomic gamma/delta T cells are both numerically and phenotypically unbalanced provides further evidence that immunological abnormalities are integral features of DS.