ZETA-CHAIN AND CD28 ARE POORLY EXPRESSED ON T-LYMPHOCYTES FROM CHRONIC LYMPHOCYTIC-LEUKEMIA

We have analyzed the expression of the zeta (zeta) chain of the T cell receptor/CD3 complex and the co-stimulatory molecule CD28 by dual col our immunofluorescence on T lymphocytes from patients with B cell chro nic lymphocytic leukemia (CLL). zeta chain was significantly reduced o n CD3-positive lymphocytes from 33 patients compared with normal contr ols (P < 0.0001). The values were lower in stages B and C than in stag e A. In five patients tested in partial remission the values were norm al. CD28, investigated in CD3, CD4 and CD8 positive T cells from 18 CL L patients appeared to be reduced in the three subsets but more marked in CD8-positive lymphocytes. The loss of zeta chain and CD28 in a pro portion of circulating T lymphocytes from CLL may underlie some of the known functional abnormalities of these cells and the immunodeficienc y associated with the disease.