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CD32 is enriched on CD4dimCD8bright T cells
Amber K Virdi1, Jennillee Wallace1, Hannah Barbian1
1Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL, United States of America.
Insights
CD32 is highly expressed on double positive T cells, including CD4dimCD8bright T cells, irrespective of HIV status. This finding suggests CD32
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- CD4dimCD8bright T cells are a distinct, highly activated CD8+ T cell population.
- CD32 (Fc gamma receptor IIa) has been implicated in HIV latency and T cell activation.
- Previous work established CD4dimCD8bright T cells as activated, anti-HIV, and HIV-infected.
Purpose of the Study:
- To investigate CD32 expression on CD4dimCD8bright T cells in the context of HIV infection.
- To determine if CD32 expression on these cells correlates with HIV status, CD4 count, or viral load.
Main Methods:
- Flow cytometry was used to quantify CD32 expression.
- Peripheral blood samples from HIV-negative and HIV-positive individuals were analyzed.
- CD32 frequency was assessed on CD4dimCD8bright T cells and CD4+ T cells.
Main Results:
- CD32 was significantly higher on CD4dimCD8bright T cells compared to CD4+ T cells in both HIV-negative (60% vs 17%) and HIV-positive (54% vs 12%) individuals.
- CD32 expression on CD4dimCD8bright T cells did not correlate with CD4 count or viral load.
- Elevated CD32 expression was observed on other double-positive T cell populations regardless of HIV serostatus.
Conclusions:
- CD32 is enriched on double-positive T cells, including CD4dimCD8bright T cells, irrespective of HIV serostatus.
- The specific functional role of CD32 on these double-positive T cells requires further investigation.
Abstract:
CD4dimCD8bright T cells, a genuine population of CD8+ T cells, are highly activated and cytolytic. Recently, the low affinity IgG Fc fragment receptor CD32a was described as marker of HIV latency while others reported that CD32a is associated with T cell activation. Given that we have previously established that CD4dimCD8bright T cells are highly activated, mediate anti-HIV responses, and are infected by HIV, we assessed here CD32 expression on CD4dimCD8bright T cells in context of HIV. CD32 frequency on peripheral CD4dimCD8bright and CD4+ T cells was determined by flow cytometry among HIV negative and HIV positive patients. We report that among HIV- individuals, mean CD32 percent expression was 60% on CD4dimCD8bright T cells and 17% on CD4+ T cells (p<0.01). Among HIV+ patients, mean CD32 percent expression was 54% on CD4dimCD8bright T cells and 12% on CD4+ T cells (p<0.001). CD32 expression on CD4dimCD8bright T cells did not correlate with CD4 count and viral load and was not different by HIV serostatus. CD32 was also higher on other double positive T cell populations in both HIV negative and HIV positive donors in comparison to their single positive T cell counterpart. Together, these studies indicate that CD32 is enriched on double positive T cells regardless of HIV serostatus. The functional role of CD32 on these double positive T cells remains to be elucidated.
