Immunologic alterations in xeroderma pigmentosum patients.

Nine xeroderma pigmentosum (XP) patients were investigated. In comparison to a normal control group the XP patients had a reduced OKT-4 lymphocyte subpopulation, reduced response of lymphocytes to phytohemagglutinin in autologous serum, and diminished delayed hypersensitivity skin reaction. The possible contribution of ultraviolet irradiation to the observed immunologic alterations, and the link of these alterations to the susceptibility of patients for malignant transformation is discussed.