Rajendra Pahwa

Upregulation of IL-21 Receptor on B Cells and IL-21 Secretion Distinguishes Novel 2009 H1N1 Vaccine Responders from Nonresponders among HIV-Infected Persons on Combination Antiretroviral Therapy

Mechanisms underlying failure of novel 2009 H1N1 influenza vaccine-induced Ab responses in HIV-infected persons are poorly understood. This study prospectively evaluated 16 HIV-infected patients on combination antiretroviral therapy and eight healthy controls (HC) who received a single 15 μg dose of nonadjuvanted novel 2009 H1N1 influenza vaccine during the 2009 H1N1 epidemic. Peripheral blood was collected at baseline (T0) and at 7 d (T1) and 28 d (T2) postvaccination for evaluation of immune responses. Prevaccination hemagglutination inhibition Ab titer was <1:20 in all except one study participant. At T2, all HC and 8 out of 16 patients (50%) developed a vaccine-induced Ab titer of ≥1:40. Vaccine responder (R) and vaccine nonresponder patients were comparable at T0 in age, CD4 counts, virus load, and B cell immunophenotypic characteristics. At T2, HC and R patients developed an expansion of phenotypic and functional memory B cells and ex vivo H1N1-stimulated IgG Ab-secreting cells in an ELISPOT assay. The memory B cell response was preceded by a significant expansion of plasmablasts and spontaneous H1N1-specific Ab-secreting cells at T1. At T2, HC and R patients also exhibited significant increases in serum IL-21 levels and in the frequency and mean fluorescence intensity of IL-21R–expressing B cells, which correlated with serum H1N1 Ab titers. Vaccine nonresponder patients failed to develop the above-described vaccine-induced immunologic responses. The novel association of novel 2009 H1N1 vaccine-induced Ab responses with IL-21/IL-21R upregulation and with development of memory B cells and plasmablasts has implications for future research in vaccine design.

CD8+ T Cells in HIV Disease Exhibit Cytokine Receptor Perturbation and Poor T Cell Receptor Activation but Are Responsive to γ-Chain Cytokine–Driven Proliferation

BACKGROUNDnCytokines are important for inducing T cell maturation, proliferation, and survival. Despite the known dysregulation of cytokines in human immunodeficiency virus (HIV) infection, cytokine receptor expression is relatively unexplored.nnnMETHODSnWe examined maturation markers (naive, central memory, effector memory, and effector); the cytokine receptors interleukin (IL)-2R beta , common gamma (C gamma ) chain, IL-7R alpha , IL-15R alpha; and proliferative responses of T cells in a cohort of HIV-infected pediatric patients (median age, 14.82 years) receiving antiretroviral therapy, arbitrarily designated as immunologic responders (group I) and nonresponders (group II) on the basis of a CD4+ T cell count cutoff of 25%.nnnRESULTSnPatients had increased percentages of effector memory CD8+ T cells, in comparison with those in healthy control subjects, with reduced expression of IL-7R alpha in the central memory and effector memory subsets and of the C gamma chain in all maturation subsets of CD8+ T cells. IL-7R alpha +CD8+ T cell percentages were directly correlated with CD4+ T cell percentages. In immunologic nonresponders, anti-CD3+ or HIV Gag antigen-induced CD8+ T cell proliferation was impaired, but proliferation in response to the homeostatic cytokines IL-2 and IL-15 was preserved.Conclusions. Cytokine receptor deficiencies may contribute to immune deficiency in HIV-infected patients, and gamma -chain-utilizing cytokines may play an important role in vivo in maintaining the memory subsets of T cells in patients with CD4+ T cell deficiency.

Innate immune defects correlate with failure of antibody responses to H1N1/09 vaccine in HIV-infected patients

BACKGROUNDnMechanisms underlying the failure of influenza vaccine-induced antibody responses in HIV-infected persons are poorly understood.nnnOBJECTIVEnTo investigate innate immune factors regulating B-cell function in HIV-infected persons and to correlate them with serologic responses to H1N1/09 vaccine.nnnMETHODSnWe evaluated immunologic characteristics of 17 HIV-infected patients and 8 healthy controls (HCs) at 0, 7, and 28 days (designated T0, T1, and T2) following a single 15-μg dose of nonadjuvanted H1N1/09 influenza vaccine by using flow cytometry, ELISpot, and ELISA. All HCs and 9 patients (53%) seroconverted with >1:40 hemagglutination inhibition antibody titer at T2.nnnRESULTSnIn vaccine responders and HCs, serum levels of BAFF (B cell-activating factor) and APRIL (a proliferation-inducing ligand) increased from T0 to T2 in conjunction with increases in frequencies of memory B cells. Concurrently, receptors for these factors showed changes, with increases in expression of TACI (transmembrane activator and calcium modulator and cyclophilin ligand interactor) and decreases in BAFF receptor in memory B cells. IL-2 secreting cells and IgG antibody-secreting cells increased at T2 in vaccine responders and HCs in exxa0vivo H1N1 antigen-stimulated cultures. These immunologic responses were not evident at T1 and were deficient in vaccine nonresponder patients at T2. At T0, vaccine nonresponders had lower frequencies of BAFF receptor and TACI-expressing memory B cells than did responders.nnnCONCLUSIONnImpaired memory B-cell responses, deficiencies in serum BAFF and APRIL, and alterations in their receptors on B cells were associated with failure of H1N1/09 influenza vaccine responses among virologically controlled HIV-infected patients.

Isolation and expansion of human natural T regulatory cells for cellular therapy

Natural T regulatory cells (nTregs) play a key role in inducing and maintaining immunological tolerance. Cell-based therapy using purified nTregs is under consideration for several conditions, but procedures employed to date have resulted in cell populations that are contaminated with cytokine secreting effector cells. We have established a method for isolation and ex vivo expansion of human nTregs from healthy blood donors for cellular therapy aimed at preventing allograft rejection in organ transplants. The Robosep instrument was used for initial nTreg isolation and rapamycin was included in the expansion phase of cell cultures. The resulting cell population exhibited a stable CD4(+)CD25(++bright)Foxp3(+) phenotype, had potent functional ability to suppress CD4(+)CD25(negative) T cells without evidence of conversion to effector T cells including TH17 cells, and manifested little to no production of pro-inflammatory cytokines upon in vitro stimulation. Boolean gating analysis of cytokine-expressing cells by flow cytometry for 32 possible profile end points revealed that 96% of expanded nTregs did not express any cytokine. From a single buffy coat, approximately 80 million pure nTregs were harvested after expansion under cGMP conditions; these cell numbers are adequate for infusion of approximately one million cells kg⁻¹ for cell therapy in clinical trials.

Paradoxical aging in HIV: Immune senescence of B Cells is most prominent in young age

Combination antiretroviral therapies (cART) can lead to normal life expectancy in HIV-infected persons, and people aged >50 yrs represent the fastest growing HIV group. Although HIV and aging are independently associated with impaired humoral immunity, immune status in people aging with HIV is relatively unexplored. In this study influenza vaccination was used to probe age associated perturbations in the B cell compartment of HIV-negative “healthy controls” (HC) and virologically controlled HIV-infected participants on cART (HIV) (n=124), grouped by age as young (<40 yrs), middle-aged (40-59yrs) or old (≥60 yrs). H1N1 antibody response at d21 post-vaccination correlated inversely with age in both HC and HIV. Immunophenotyping of cryopreserved PBMC demonstrated increased frequencies of double negative B cells and decreased plasmablasts in old compared to young HC. Remarkably, young HIV were different from young HC but similar to old HC in B cell phenotype, influenza specific spontaneous (d7) or memory (d21) antibody secreting cells. We conclude that B cell immune senescence is a prominent phenomenon in young HIV in comparison to young HC, but distinctions between old HIV and old HC are less evident though both groups manifest age-associated B cell dysfunction.

Peripheral T follicular helper cells from H1N1/09 vaccine nonresponders fail to induce antigen-specific antibody production in vitro

Methods The study was conducted in cryopreserved cells of 16 HIVinfected, ART-treated individuals and 8 healthy donors (HD) who had been given a single dose of H1N1/09 influenza vaccine in 2009. Only 8 of the 16 patients and all HD had a flu-Ab response at 4 wks post vaccination. Vaccine responder (VR) and non responder (VNR) patients were equivalent in mean age, viral load, CD4 and CD8 T and B cells. B (CD20+) and TFH (CD3+ CD4+ CD45RA– CXCR5+) cells were purified by cell sorting on a FACS ARIA and co-cultured. IgG levels in culture supernatants were determined by ELISA. B and T cell phenotypic analysis was performed by multicolor flow cytometry. Differences between groups were analyzed by Student t-test or the 2-sample Wilcoxon rank-sum (Mann-Whitney) test.

Impaired CCR7 Expression on Plasmacytoid Dendritic Cells in HIV Infected Children on HAART With Virologic Failure

Materials and methods Patients with perinatal HIV infection (n = 19, ages 11–18 yr, on HAART) were classified as immunologic responders (IR+; CD4>25%), and virologic responders (VR; plasma HIV RNA < 400 copies/mL). mDC (Lin-, HLA DR+CD11c+) and pDC (Lin-, HLA DR+ CD11c-) were evaluated in a novel whole blood assay by flow cytometry for expression of maturation markers CD83, CD80, homing receptor CCR7 and intracellular cytokines (TNF-α and IFN-α) after short-term stimulation with a TLR7/8 agonist, resiquimod.