title: Peripheral T Follicular Helper Cells Are the Major HIV Reservoir within Central Memory CD4 T Cells in Peripheral Blood from Chronically HIV-Infected Individuals on Combination Antiretroviral Therapy.
abstract: In this study, we examined the peripheral blood (PB) central memory (TCM) CD4(+) T cell subsets designated peripheral T follicular helper cells (pTfh cells) and non-pTfh cells to assess HIV permissiveness and persistence. Purified pTfh and non-pTfh cells from healthy HIV-negative donors were tested for HIV permissiveness using green fluorescent protein (GFP)-expressing HIV-1NL4-3/Ba-L, followed by viral reactivation using beads coated with anti-CD3/anti-CD28 monoclonal antibodies. The role of pTfh cells in HIV persistence was analyzed in 12 chronically HIV-1 infected patients before and 48 weeks after initiation of raltegravir-containing combination antiretroviral therapy (cART). Total cellular HIV-1 DNA and episomes containing two copies of the viral long terminal repeat (2LTR circles) were analyzed in using droplet digital PCR in the purified pTfh and non-pTfh cells. Activation-inducible HIV p24 expression was determined by flow cytometry. Results indicate that pTfh cells, in particular PD1(+) pTfh cells, showed greater permissiveness for HIV infection than non-pTfh cells. At week 48 on cART, HIV DNA levels were unchanged from pre-cART levels, although a significant decrease in 2LTR circles was observed in both cell subsets. Inducible HIV p24 expression was higher in pTfh cells than in non-pTfh cells, with the highest frequencies in the PD1(+) CXCR3(-) pTfh cell subset. Frequencies of HLADR(+) CD38(+) activated CD4 T cells correlated with 2LTR circles in pTfh and non-pTfh cells at both time points and with p24(+) cells at entry. In conclusion, among CD4 TCM cells in PB of aviremic patients on cART, pTfh cells, in particular the PD1(+) CXCR3(-) subset, constitute a major HIV reservoir that is sustained by ongoing residual immune activation. The inducible HIV p24 assay is useful for monitoring HIV reservoirs in defined CD4 T cell subsets.
  
  
  OBJECTIVE
  Identification of the type and nature of the cellular compartments of circulating HIV reservoirs is important for targeting of HIV cure strategies. In lymph nodes (LN), a subset of CD4 T cells called T follicular helper (Tfh) cells are preferentially infected by HIV. Central memory (TCM) CD4 T cells are the major cellular reservoir for HIV in peripheral blood and contain a subset of CD4 TCM cells expressing chemokine receptor CXCR5 similar in function to LN Tfh cells termed peripheral Tfh (pTfh) cells. We found that the circulating pTfh cells are highly susceptible to HIV infection and that in HIV-infected patients, HIV persists in these cells following plasma virus suppression with potent cART. These pTfh cells, which constitute a subset of TCM CD4 T cells, can be readily monitored in peripheral blood to assess HIV persistence.
authors.affiliation: Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida, USA Miami Center For AIDS Research, Miami, Florida, USA.
authors.forename: Suresh
authors.initials: S
authors.lastname: Pallikkuth
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, USA Miami Center For AIDS Research, Miami, Florida, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Sharkey
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, USA Miami Center For AIDS Research, Miami, Florida, USA.
authors.forename: Dunja Z
authors.initials: DZ
authors.lastname: Babic
authors.affiliation: Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida, USA Miami Center For AIDS Research, Miami, Florida, USA.
authors.forename: Sachin
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida, USA Miami Center For AIDS Research, Miami, Florida, USA.
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: Stone
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, USA Miami Center For AIDS Research, Miami, Florida, USA.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Fischl
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, USA Miami Center For AIDS Research, Miami, Florida, USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Stevenson
authors.affiliation: Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida, USA Miami Center For AIDS Research, Miami, Florida, USA spahwa@med.miami.edu.
authors.forename: Savita
authors.initials: S
authors.lastname: Pahwa
mesh_terms: D000328:Adult; D044966:Anti-Retroviral Agents / Q000627:therapeutic use*; D015496:CD4-Positive T-Lymphocytes / Q000821:virology*; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification; D016655:HIV Core Protein p24 / Q000032:analysis; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology*; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008875:Middle Aged; D010865:Pilot Projects; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D011533:Proviruses / Q000235:genetics / Q000302:isolation & purification; D016176:T-Lymphocyte Subsets / Q000821:virology*; D014775:Virus Activation
chemical_list: D044966:Anti-Retroviral Agents; D004279:DNA, Viral; D016655:HIV Core Protein p24