Familial CDS deficiency due to a mutation in the CD8 alpha gene

CD8 glycoproteins play an important role in both the maturation and functio n of MHC class I-restricted T lymphocytes. A 25-year-old man, from a consan guineous family, with recurrent bacterial infections and total absence of C D8(+) cells, was studied. Ab deficiencies and ZAP-70 and TAP defects were r uled out. A missense mutation (gly90-->ser) in both alleles of the immunogl obulin domain of the CD8 alpha gene was shown to correlate with the absence of CD8 expression found in the patient and two sisters. Conversely, high p ercentages of CD4(-)CD8(-)TCR alpha beta (+) T cells were found in the thre e siblings. A novel autosomal recessive immunologic defect characterized by absence of CD8(+) cells is described. These findings may help to further u nderstanding of the role of CD8 molecules in human immune response.