Characterising B cell numbers and memory B cells in HIV infected and uninfected Malawian adults

Abstract

Background: Untreated human immunodeficiency virus (HIV) disease disrupts B cell populations causing reduced memory and reduced naïve resting B cells leading to increases in specific co-infections and impaired responses to vaccines. To what extent antiretroviral treatment reverses these changes in an African population is uncertain.

Methods: A cross-sectional study was performed. We recruited HIV-uninfected and HIV-infected Malawian adults both on and off antiretroviral therapy attending the Queen Elizabeth Central hospital in Malawi. Using flow cytometry, we enumerated B cells and characterized memory B cells and compared these measurements by the different recruitment groups.

Results: Overall 64 participants were recruited - 20 HIV uninfected (HIV-), 30 HIV infected ART naïve (HIV+N) and 14 HIV-infected ART treated (HIV+T). ART treatment had been taken for a median of 33 months (Range 12-60 months). Compared to HIV- the HIV+N adults had low absolute number of naïve resting B cells (111 vs. 180 cells/μl p = 0.008); reduced memory B cells (27 vs. 51 cells/μl p = 0.0008). The HIV+T adults had B-cell numbers similar to HIV- except for memory B cells that remained significantly lower (30 vs. 51 cells/μl p = 0.02). In the HIV+N group we did not find an association between CD4 count and B cell numbers.

Conclusions: HIV infected Malawian adults have abnormal B-cell numbers. Individuals treated with ART show a return to normal in B-cell numbers but a persistent deficit in the memory subset is noted. This has important implications for long term susceptibility to co-infections and should be evaluated further in a larger cohort study.

Figure 1

Absolute B cell counts from HIV negative, HIV positive ART naïve and on ART. Medians (10^th and 90^th percentiles) of absolute B cell counts (x10³cells/ml) in HIV negative (n = 20), HIV infected subjects ART naïve (n = 30) and HIV infected subjects on ART (n = 14).

Figure 2

Scatter plots evaluating correlation between CD4 T cell and absolute B cell counts and between absolute B cell counts and total lymphocyte counts in both HIV+N and HIV+T. Scatter plots evaluating correlation between CD4 T cell counts and absolute B cell counts in HIV positive adults ART naïve (Figure 2a) and HIV positive adults on ART (Figure 2b). Correlation between absolute B cell counts and total lymphocyte counts in HIV positive adults ART naïve (Figure 2c) and HIV positive adults on ART (Figure 2d)