Abstract
BackgroundHIV infection is associated with more frequent and severe episodes of malaria and may be the result of altered malaria-specific B cell responses. However, it is poorly understood how HIV and the associated lymphopenia and immune activation affect malaria-specific antibody responses.MethodsHIV infected and uninfected adults were recruited from Bondo subcounty hospital in Western Kenya at the time of HIV testing (antiretroviral and co-trimoxazole prophylaxis naïve). Total and Plasmodium falciparum apical membrane antigen-1 (AMA1) and glutamate rich protein-R0 (GLURP-R0) specific IgM, IgG and IgG subclass concentrations was measured in 129 and 52 of recruited HIV-infected and uninfected individuals, respectively. In addition, HIV-1 viral load (VL), CD4+ T cell count, and C-reactive protein (CRP) concentration was quantified in study participants. Antibody levels were compared based on HIV status and the associations of antibody concentration with HIV-1 VL, CD4+ count, and CRP levels was measured using Spearman correlation testing.ResultsAmong study participants, concentrations of IgM, IgG1 and IgG3 antibodies to AMA1 and GLURP-R0 were higher in HIV infected individuals compared to uninfected individuals (all p < 0.001). The IgG3 to IgG1 ratio to both AMA1 and GLURP-R0 was also significantly higher in HIV-infected individuals (p = 0.02). In HIV-infected participants, HIV-1 VL and CRP were weakly correlated with AMA1 and GLURP-R0 specific IgM and IgG1 concentrations and total (not antigen specific) IgM, IgG, IgG1, and IgG3 concentrations (all p < 0.05), suggesting that these changes are related in part to viral load and inflammation.ConclusionsOverall, HIV infection leads to a total and malaria antigen-specific immunoglobulin production bias towards higher levels of IgM, IgG1, and IgG3, and HIV-1 viraemia and systemic inflammation are weakly correlated with these changes. Further assessments of antibody affinity and function and correlation with risk of clinical malaria, will help to better define the effects of HIV infection on clinical and biological immunity to malaria.
Highlights
human immunodeficiency virus (HIV) infection is associated with more frequent and severe episodes of malaria and may be the result of altered malaria-specific B cell responses
These B cell phenotypic changes do not fully explain why there is clinically impaired B cell immunity, in cases where antigen specific antibody responses are maintained despite coexisting B cell phenotypic abnormalities, as has been described with malaria and HIV coinfection [12]
The data presented here demonstrates that HIV-infected individuals living a highly malaria endemic region of Kenya have higher levels of IgM, IgG1 and IgG3 antibodies to the P. falciparum antigens apical membrane antigen-1 (AMA1) and GLURP-R0 when compared to HIV-uninfected individuals
Summary
HIV infection is associated with more frequent and severe episodes of malaria and may be the result of altered malaria-specific B cell responses. Despite the fact that human immunodeficiency virus (HIV) infection is largely considered a disease of altered intracellular immunity, it has been shown to have a major impact on the B cell compartment. Diminished T follicular helper cell support, altered responsiveness to T cell stimulation, and intrinsic B cell dysfunction have all been considered as a cause of these impairments and recently phenotypically exhausted B cells have been described in the setting of HIV infection [1, 7,8,9,10,11] These B cell phenotypic changes do not fully explain why there is clinically impaired B cell immunity, in cases where antigen specific antibody responses are maintained despite coexisting B cell phenotypic abnormalities, as has been described with malaria and HIV coinfection [12]
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