CD8 lymphocytopenia caused by ZAP-70 deficiency

The discovery of decreased ZAP-70 expression in a subset of severely immuno deficient patients first revealed the importance of ZAP-70 in T-lymphocyte maturation and function. Patients with ZAP-70 kinase deficiency demonstrate a selective defect in CD8 T-cell differentiation, possessing normal number s of CD4 T cells and B lymphocytes. Subsequent studies have shown that ZAP- 70 is essential for signaling from the T-cell receptor complex in developin g lymphocytes and circulating mature T lymphocytes. This article provides a n overview of the role of the ZAP-70 kinase in normal T cells, and discusse s the abnormalities that arise in its absence.