Increased Frequency of CD27 - (Naive) B Cells and Their Phenotypic Alteration in HIV Type 1-Infected Patients

To investigate HIV-1-related B cell disorders, the quantity of peripheral CD27 negative (CD27^-) B cells, their CD38, CD95, and bcl-2 intensities, and their apoptosis susceptibility were examined by flow cytometry analysis in 16 drug-naive patients, 27 HAART-treated patients, and 20 uninfected controls. CD27^- B cells have been recognized as naive B cells. The mean percentage of CD27^- B cells was significantly higher in drugnaive patients (88.1%) and in HAART-treated patients (83.9%) than in controls (68.6%) (p < 0.01). The intensities of CD38 and CD95 on CD27^- B cells were significantly higher in drug-naive patients than in controls (p < 0.01). The intensity of CD95 on CD27^- B cells in HAART-treated patients was lower than that of drug-naive patients, but significantly higher than that of controls (p < 0.01). The intensity of bcl-2 on CD27^- B cells in drug-naive patients was lower than that of controls. In drug-naive patients, CD27^-B cells with high CD38 expression represented low bcl-2 expression. The CD27^- B cells of drug-naive patients showed an increased susceptibility to apoptosis, characterized by diminished cell size and a high frequency of annexin-V binding, compared with controls and HAART-treated patients. These findings suggested that HIV-1 infection affects peripheral CD27^- (naive) B cells as well as CD27⁺ (memory) B cells and that CD27^- B cells might be activated and rendered highly susceptible to apoptosis by HIV-1 infection. Some phenotypic alterations in CD27^- B cells may continue after the reduction of HIV-1 loads by effective antiviral therapy.