Short Communication: Nonprogressive HIV-1 Infection Is Associated with Expansion of IL-21R Expressing Class-Switched Memory B Cells.

HIV perturbs the functionality of B cells resulting in defective humoral responses. As efficient humoral immune responses are important in controlling HIV-disease progression, we characterized the memory B cell population for its subsets and their activation (CD38 expression) and functional [interleukin (IL)-21R expression] profile in individuals with nonprogressive [long-term nonprogressors (LTNPs), N  = 16] and progressive HIV disease (progressors, N  = 16) along with 10 HIV uninfected healthy controls (HCs). The frequencies of total memory B cells were similar in HCs and HIV-infected individuals, whereas the frequencies of unswitched memory B (UMB) cells and CD38 ⁺ UMB cells were significantly higher in progressors than LTNPs and HCs ( p  < .03). LTNPs showed higher frequencies of class-switched memory B (SMB) cells and IL-21R expressing SMB cells than seen in progressors ( p  = .019), which were similar to that seen in HCs. The %UMB cells correlated inversely ( p  = .0002, r  = -0.6053) and %SMB cells correlated positively ( p  = .0005, r  = 0.5804) with CD4 count. IL-21/IL-21R interaction is required for class switching of B cells and differentiation into antibody-secreting plasma cells. The higher expression of IL-21R on class SMB cells from LTNPs might be resulting in efficient plasma cell differentiation and the functional humoral immune response that might be responsible for mounting efficient antibody response against the encountered infections. The more insights in this area might be required to further understand the role of IL-21R expressing class SMB cells in HIV infection.