CD32-Expressing CD4 T Cells Are Phenotypically Diverse and Can Contain Proviral HIV DNA

Abstract

Efforts to both characterize and eradicate the HIV reservoir have been limited by the rarity of latently infected cells and the absence of a specific denoting biomarker. CD32a (FcγRIIa) has been proposed to be a marker for an enriched CD4 T cell HIV reservoir, but this finding remains controversial. Here, we explore the expression of CD32 on CD3+CD4+ cells in participants from two primary HIV infection studies and identify at least three distinct phenotypes (CD32low, CD32+CD14+, and CD32high). Of note, CD4 negative enrichment kits remove the majority of CD4+CD32+ T cells, potentially skewing subsequent analyses if used. CD32high CD4 T cells had higher levels of HLA-DR and HIV co-receptor expression than other subsets, compatible with their being more susceptible to infection. Surprisingly, they also expressed high levels of CD20, TCRαβ, IgD, and IgM (but not IgG), markers for both T cells and naïve B cells. Compared with other populations, CD32low cells had a more differentiated memory phenotype and high levels of immune checkpoint receptors, programmed death receptor-1 (PD-1), Tim-3, and TIGIT. Within all three CD3+CD4+CD32+ phenotypes, cells could be identified in infected participants, which contained HIV DNA. CD32 expression on CD4 T cells did not correlate with HIV DNA or cell-associated HIV RNA (both surrogate measures of overall reservoir size) or predict time to rebound viremia following treatment interruption, suggesting that it is not a dominant biomarker for HIV persistence. Our data suggest that while CD32+ T cells can be infected with HIV, CD32 is not a specific marker of the reservoir although it might identify a population of HIV enriched cells in certain situations.

CD32 expressing doublets in HIV-infected gut-associated lymphoid tissue are associated with a T follicular helper cell phenotype

“…We previously reported partial enrichment for HIV DNA in CD4 T cells associating with CD32 in some individuals, 18 prior to the finding that CD32 + CD4 + flow cytometric events comprised doublets. We therefore wished to explore the phenotype and potential physiological-versus artefactual-relevance of T cells engaged in doublet formation, whether they were also present in GALT, and any possible association with the GALT HIV reservoir.…”

“…Recent work suggesting that CD32a (a low-affinity IgG receptor not generally expressed on T cells 10 ) was a specific marker for latent HIV infection 11 was initially supported by studies showing that CD32 may be found on cells that are transcriptionally active, and was associated with HIV DNA levels in some patients. [12][13][14][15][16][17][18][19] However, the finding that CD32 co-expression with CD4 is predominantly due to T-cell-B-cell doublets 17 likely undermines the argument that CD32 is a definitive marker of latency.…”

Current Status of Latency Reversing Agents Facing the Heterogeneity of HIV-1 Cellular and Tissue Reservoirs

“…Recently, the expression of CD32a has been reported as a potential marker of memory CD4 + T cells harboring a replication-competent latent virus in aviremic patients under ART (Descours et al, 2017;Darcis et al, 2019). The role of CD32a as a cellular marker of HIV-1 reservoirs has been the subject of several works Martin et al, 2018;Osuna et al, 2018;Thornhill et al, 2019). A complete study presented at CROI by Darcis et al (CROI 2019, Poster 346 -CD32 + CD4 + T cells are enriched in HIV-1 DNA) showed that active CD4 + T cells co-expressing HLA-DR and CD32a are highly enriched with HIV-1 DNA.…”

Measuring the Success of HIV-1 Cure Strategies

“…Recently, CD32+ CD4 T cells have been proposed to be a major host of the LR, whereby selection of this cell population resulted in significant enrichment of inducible provirus (Descours et al, 2017;Darcis et al, 2020). Conflicting reports, however, have failed to replicate this finding and the contribution of CD32+ CD4 T cells to HIV-1 persistence and rebound remains controversial (Abdel-Mohsen et al, 2018;Badia et al, 2018;Bertagnolli et al, 2018;Martin et al, 2018;Osuna et al, 2018;Pérez et al, 2018). Nonetheless, the use of CD32 as a marker of latent infection is a topic of particular interest and may provide a mechanism by which the LR can be specifically targeted.…”