Level of TCR zeta chain is abnormally low in fresh, unstimulated T cells from patients either in remission of Hodgkin's disease or with relapsed disease v that in T cells from normal donors (□). Stimulation of T cells with IL-2, anti-CD3, and HLA-mismatched PBMC resulted in upregulation of the TCR zeta-chain expression as assessed by FACs analysis (▪).