Quantitative and qualitative defects in CD1d-restricted T cells have been demonstrated in human and murine autoimmune diseases. To investigate the transcriptional consequences of T cell receptor activation in human Vα24JαQ T cell clones, DNA microarrays were used to quantitate changes in mRNA levels after anti-CD3 stimulation of clones derived from identical twins discordant for type 1 diabetes and IL-4 secretion. Activation resulted in significant modulation of 226 transcripts in the IL-4 secreting clone and 86 in the IL-4-null clone. Only 28 of these genes were in common. The differences observed suggest both ineffective differentiation of diabetic Vα24JαQ T cells and a role for invariant T cells in the recruitment and activation of cells from the myeloid lineage.