Immune responses to fractionated cytomegalovirus (CMV) antigens after HIV infection. Loss of cellular and humoral reactivity to antigens recognized by HIV^-, CMV⁺ individuals

In order to delineate the molecular pathogenesis of the increased susceptibility to CMV disease in HIV infection, the patterns of antigen responsiveness in HIV-infected and non-infected individuals were investigated. CMV was fractionated by SDS-PAGE and electroblotted onto nitrocellulose. Lymphoproliferative responses of healthy HIV^-, CMV⁺ individuals and HIV⁺, CMV⁺ asymptomatic patients to a whole CMV antigen preparation and to 20 fractions of nitrocellulose-bound CMV were then compared. Three fractions of approximate molecular weight of 130-165, 65-75, and 55-65 kD appeared to contain the major T cell stimulating antigens for HIV^-, CMV⁺ individuals. A statistically significant depression of responses to fractions containing antigens in the ranges of 130-165 kD and 55-65 kD but not to whole CMV was seen in HIV⁺ individuals compared with controls. In healthy controls, the sum of the proliferative responses as measured by ³H-thymidine uptake to these three major fractions was approximately equal to the response to a whole CMV antigen preparation, whereas it was less than half of this response in five out of six HIV⁺ subjects. When antibody activities to CMV antigens were analysed by immunoblotting of sera from the two subject groups and also sera of ARC and AIDS patients, a selective loss of reactivity was revealed in 10 out of 19 HIV⁺ subjects to a band of 26-28 kD whereas all 15 HIV^-, CMV⁺ controls recognized this band. Serum IgG and IgM values were both significantly higher in HIV⁺ individuals than in controls. These findings suggest that specific lesions in the repertoire of immune responsiveness to CMV antigens occur in HIV⁺ individuals.