Decrease in numbers of naive and resting B cells in HIV-infected Kenyan Adults leads to a proportional increase in total and plasmodium falciparum-specific atypical memory B cells

Human immunodeficiency virus type 1 (HIV-1) infection is associated with B cell activation and exhaustion, and hypergammaglobulinemia. How these changes influence B cell responses to coinfections such as malaria is poorly understood. To address this, we compared B cell phenotypes and Abs specific for the Plasmodium falciparum vaccine candidate apical membrane Ag-1 (AMA1) in HIV-infected and uninfected adults living in Kenya. Surprisingly, HIV-1 infection was not associated with a difference in serum AMA1-specific Ab levels. HIV-infected individuals had a higher proportion of total atypical and total activated memory B cells (MBCs). Using an AMA1 tetramer to detect AMA1-specific B cells, HIV-infected individuals were also shown to have a higher proportion of AMA1-specific atypical MBCs. However, this proportional increase resulted in large part from a loss in the number of naive and resting MBCs rather than an increase in the number of atypical and activated cells. The loss of resting MBCs and naive B cells was mirrored in a population of cells specific for an Ag to which these individuals were unlikely to have been chronically exposed. Together, the data show that changes in P. falciparum Ag-specific B cell subsets in HIV-infected individuals mirror those in the overall B cell population, and suggest that the increased proportion of atypical MBC phenotypes found in HIV- 1-infected individuals results from the loss of naive and resting MBCs.