CD4 T-cell Proliferative Responses Research Articles

Distinct susceptibility of HIV vaccine vector-induced CD4 T cells to HIV infection.

The concerns raised from adenovirus 5 (Ad5)-based HIV vaccine clinical trials, where excess HIV infections were observed in some vaccine recipients, have highlighted the importance of understanding host responses to vaccine vectors and the HIV susceptibility of vector-specific CD4 T cells in HIV vaccination. Our recent study reported that human Ad5-specific CD4 T cells induced by Ad5 vaccination (RV156A trial) are susceptible to HIV. Here we further investigated the HIV susceptibility of vector-specific CD4 T cells induced by ALVAC, a canarypox viral vector tested in the Thai trial RV144, as compared to Ad5 vector-specific CD4 T cells in the HVTN204 trial. We showed that while Ad5 vector-specific CD4 T cells were readily susceptible to HIV, ALVAC-specific CD4 T cells in RV144 PBMC were substantially less susceptible to both R5 and X4 HIV in vitro. The lower HIV susceptibility of ALVAC-specific CD4 T cells was associated with the reduced surface expression of HIV entry co-receptors CCR5 and CXCR4 on these cells. Phenotypic analyses identified that ALVAC-specific CD4 T cells displayed a strong Th1 phenotype, producing higher levels of IFN-γ and CCL4 (MIP-1β) but little IL-17. Of interest, ALVAC and Ad5 vectors induced distinct profiles of vector-specific CD8 vs. CD4 T-cell proliferative responses in PBMC, with ALVAC preferentially inducing CD8 T-cell proliferation, while Ad5 vector induced CD4 T-cell proliferation. Depletion of ALVAC-, but not Ad5-, induced CD8 T cells in PBMC led to a modest increase in HIV infection of vector-specific CD4 T cells, suggesting a role of ALVAC-specific CD8 T cells in protecting ALVAC-specific CD4 T cells from HIV. Taken together, our data provide strong evidence for distinct HIV susceptibility of CD4 T cells induced by different vaccine vectors and highlight the importance of better evaluating anti-vector responses in HIV vaccination.

Anti-T cell immunoglobulin and mucin domain-2 monoclonal antibody exacerbates collagen-induced arthritis by stimulating B cells

IntroductionT cell immunoglobulin and mucin domain-2 (TIM-2) has been shown to regulate CD4 T cell activation. However, the role of TIM-2 in the autoimmune disease models has not been clarified yet. In this study, we investigated the effects of anti-TIM-2 monoclonal antibodies (mAbs) in collagen-induced arthritis (CIA) to determine whether TIM-2 contributes to the development of T helper (Th) 1 or Th17 cells and joint inflammation.MethodsDBA/1 mice were treated with anti-TIM-2 mAbs during the early or late phase of CIA. Type II collagen (CII)-specific CD4 T-cell proliferative response and cytokine production were assessed from lymph node cell culture. The serum levels of CII-specific antibody were measured by ELISA. The expression of TIM-2 on CD4 T cells or B cells was determined by flow cytometric analysis.ResultsAdministration of anti-TIM-2 mAbs in early phase, but not late phase, significantly exacerbated the development of CIA. Although anti-TIM-2 mAbs treatment did not affect the development of Th1 or Th17 cells in the draining lymph node, the serum levels of anti-CII antibodies were significantly increased in the anti-TIM-2-treated mice. TIM-2 expression was found on splenic B cells and further up-regulated by anti-immunoglobulin (Ig)M, anti-CD40, and interleukin(IL)-4 stimulation. In contrast, CD4 T cells did not express TIM-2 even when stimulated with both anti-CD3 and anti-CD28 mAbs. Interestingly, anti-TIM-2 mAbs enhanced proliferation and antibody production of activated B cells in vitro.ConclusionsTIM-2 signaling influences both proliferation and antibody production of B cells during the early phase of CIA, but not induction of Th1 or Th17 cells.

The CD8 and CD4 T-Cell Response against Kaposi's Sarcoma-Associated Herpesvirus Is Skewed Towards Early and Late Lytic Antigens

Kaposi's sarcoma-associated herpesvirus (KSHV) is causally related to Kaposi's sarcoma (KS), the most common malignancy in untreated individuals with HIV/AIDS. The adaptive T-cell immune response against KSHV has not been fully characterized. To achieve a better understanding of the antigenic repertoire of the CD8 and CD4 T-cell responses against KSHV, we constructed a library of lentiviral expression vectors each coding for one of 31 individual KSHV open reading frames (ORFs). We used these to transduce monocyte-derived dendritic cells (moDCs) isolated from 14 KSHV-seropositive (12 HIV-positive) and 7 KSHV-seronegative (4 HIV-positive) individuals. moDCs were transduced with up to 3 KSHV ORFs simultaneously (ORFs grouped according to their expression during the viral life cycle). Transduced moDCs naturally process the KSHV genes and present the resulting antigens in the context of MHC class I and II. Transduced moDCs were cultured with purified autologous T cells and the CD8 and CD4 T-cell proliferative responses to each KSHV ORF (or group) was assessed using a CFSE dye-based assay. Two pools of early lytic KSHV genes ([ORF8/ORF49/ORF61] and [ORF59/ORF65/K4.1]) were frequently-recognized targets of both CD8 and CD4 T cells from KSHV seropositive individuals. One pool of late lytic KSHV genes ([ORF28/ORF36/ORF37]) was a frequently-recognized CD8 target and another pool of late genes ([ORF33/K1/K8.1]) was a frequently-recognized CD4 target. We report that both the CD8 and CD4 T-cell responses against KSHV are skewed towards genes expressed in the early and late phases of the viral lytic cycle, and identify some previously unknown targets of these responses. This knowledge will be important to future immunological investigations into KSHV and may eventually lead to the development of better immunotherapies for KSHV-related diseases.

Peptide immunotherapy for allergic diseases using a rice-based edible vaccine

Plant pollens are the most common cause of seasonal allergic disease. The number of patients undergoing treatment for allergies to the pollen of Japanese cedar (major antigens: Cry j 1 and Cry j 2) has increased steadily each year. Integration of an effective, safe and inexpensive clinical program would be greatly improved by addressing deficiencies in systemically delivered immunotherapy. We have demonstrated that feeding mice transgenic rice seeds accumulating the T-cell epitope peptides of Cry j 1 and Cry j 2 before systemic challenge with total protein of cedar pollen inhibits the development of allergen-specific IgE, IgG and CD4 T-cell proliferative responses. The levels of allergen-specific CD4 T-cell-derived allergy-associated T-helper 2 cytokine of IL-4, IL-5, and IL-13 and histamine release in serum were also significantly decreased. Moreover, clinical symptoms were inhibited in an experimental sneezing-mouse model. Plant-based edible vaccine has been shown to be effective for treatment of Japanese cedar pollinosis. When rice seeds containing T-cell epitopes derived from cedar pollen allergens were orally administered to mice, immune tolerance leading to reduction of allergen-specific IgE, T-cell proliferative reaction and histamine could be induced, resulting in suppression of allergic-specific symptoms such as sneezing.

Influence of ethnicity in the outcome of hepatitis C virus infection and cellular immune response

This study was performed to examine the immunologic basis for the apparent ethnic difference in clinical outcome of hepatitis C virus (HCV) infection between African Americans (AA) and Caucasian Americans (CA). To this end, we recruited 99 chronically HCV-infected and 31 spontaneously HCV-cleared subjects for clinical, virologic, and immunologic analysis. In particular, CD4-proliferative T-cell response to genotype 1–derived HCV antigens (core, NS3-NS5) was examined in 82 patients chronically infected with genotype 1 (54 AA, 28 CA) and in all HCV-cleared subjects (14 AA, 17 CA). HCV-specific Th1 response also was examined in 52 chronic and 13 recovered subjects. Our results showed that HCV clearance was associated with a vigorous HCV-specific Th1 response irrespective of ethnic origin. Although the HCV-specific CD4 T-cell response clearly was weaker during chronic infection, AA ethnicity in this setting was associated with a significantly greater CD4-proliferative T-cell response to HCV, particularly to the nonstructural antigens (22% AA vs. 0% CA, P = .007) as well as better clinical parameters of liver disease. Interestingly, most HCV-specific CD4 T-cell proliferative responses in AA patients were unaccompanied by concurrent interferon γ (IFN-γ) production, suggesting a dysregulated virus-specific, CD4 T-cell effector function during chronic HCV infection. In conclusion, our results suggest that host ethnicity does influence the clinical outcome and antiviral T-cell response during HCV infection. AA ethnicity is associated with a more robust antiviral CD4 T-cell response than CA ethnicity, although these T cells are limited in direct virus or disease control due to their dysfunctional nature. (H EPATOLOGY 2003;37:590-599.)

New insights into evaluating effective T-cell responses to HIV.

Towards addressing questions related to HIV pathogenesis and vaccine design we are fortunate to have the availability of the SIV-infected rhesus macaque model. The strengths of this model which include a rapid rate of progression to AIDS and knowledge of the dose route and strain of the infecting virus complement studies in HIV-infected patients in which the reagents host genetics and access to samples are more extensive and better defined. Unfortunately there is currently still too little known about the antiviral immune responses in either system to directly and accurately compare their similarities and differences and to draw any definitive conclusions. Therefore the data and views presented herein will simply reflect what has recently been discovered in both humans and non-human primate studies. (excerpt)

Lack of T-cell proliferative response to HIV-1 antigens after 1 year of highly active antiretroviral treatment in early HIV-1 disease

Virus-specific CD4 T-cell helper response, known to have a key role in maintaining a protective cytotoxic T lymphocyte (CTL) response in chronic viral infections, 1 Rosenberg ES Billingsley JM Caliendo AM et al. Vigorous HIV-1-specific CD4+ T cell responses associated with control of viremia. Science. 1997; 278: 1447-1450 Crossref PubMed Scopus (1671) Google Scholar are not usually detected in HIV-1 infected people even in early stages. 2 Carlesimo M Pontessilli O Varani AR et al. CD28 stimulation and T lymphocyte proliferative responses in HIV-1 infection. Clin Exp Immunol. 1998; 109: 406-411 Crossref Scopus (8) Google Scholar Consequently, this response may play an important part in the control of HIV-1 disease. HIV-1-specific CD4 T-cell proliferative response is associated with control of viraemia in a few untreated long-term non-progressors as well as in acutely infected people whose viraemia is reduced by highly active antiretroviral therapy (HAART) started before seroconversion. 1 Rosenberg ES Billingsley JM Caliendo AM et al. Vigorous HIV-1-specific CD4+ T cell responses associated with control of viremia. Science. 1997; 278: 1447-1450 Crossref PubMed Scopus (1671) Google Scholar By contrast, this response is absent in patients with long-standing HIV-1 infection receiving HAART. 3 Autran B Carcelain T Li TS et al. Positive effects of combined antiretroviral therapy on CD4+ T cell homeostatis and function in advanced HIV disease. Science. 1997; 277: 112-116 Crossref PubMed Scopus (1630) Google Scholar

Role of E4 in eliciting CD4 T-cell and B-cell responses to adenovirus vectors delivered to murine and nonhuman primate lungs.

Adenovirus vectors delivered to lung are being considered in the treatment of cystic fibrosis (CF). Vectors from which E1 has been deleted elicit T- and B-cell responses which confound their use in the treatment of chronic diseases such as CF. In this study, we directly compare the biology of an adenovirus vector from which E1 has been deleted to that of one from which E1 and E4 have been deleted, following intratracheal instillation into mouse and nonhuman primate lung. Evaluation of the E1 deletion vector in C57BL/6 mice demonstrated dose-dependent activation of both CD4 T cells (i.e., TH1 and TH2 subsets) and neutralizing antibodies to viral capsid proteins. Deletion of E4 and E1 had little impact on the CD4 T-cell proliferative response and cytolytic activity of CD8 T cells against target cells expressing viral antigens. Analysis of T-cell subsets from mice exposed to the vector from which E1 and E4 had been deleted demonstrated preservation of TH1 responses with markedly diminished TH2 responses compared to the vector with the deletion of E1. This effect was associated with reduced TH2-dependent immunoglobulin isotypes and markedly diminished neutralizing antibodies. Similar results were obtained in nonhuman primates. These studies indicate that the vector genotype can modify B-cell responses by differential activation of TH1 subsets. Diminished humoral immunity, as was observed with the E1 and E4 deletion vectors in lung, is indeed desired in applications of gene therapy where readministration of the vector is necessary.

Do B cells drive the diversification of immune responses?

Although the phenomenon of immunodominance of epitopes within protein antigens is well established, immune responses in which antigen persists are characterized by a great diversity of Tand B-cell responses. This is observed especially in chronic infection and autoimmunity. In this brief paper, we would like to propose a mechanism for diversification of immune responses based on the unique ability of the B cell to present the diversity of peptides from an antigen or antigenic complex required for a diverse CD4 T-cell response based on our recent studies on the role of B cells in antigen presentation to CD4 T cells in vivo (Refs 1,2 and M.J. Mamula, S. Fatehnejad and J. Craft, submitted). The activation of CD4 T cells by an exogenous protein antigen requires preseotation by a cell that can internalize the antigen, process it, and present it on the surface bound to major histocompatibility complex (MHC) class II molecules. The same APC must provide suitable costimulatory signals, the best characterized of which is the CD28 ligand B7/BB1 ~'a. Much recent data supports a role for dendritic cells (DC) in the initiation of CD4 T-cell responses to protein antigens in vWO s-7. However, earlier studies suggested that B cells were important for the induction of recall proliferative responses to protein antigens, in that mice treated from ~-;'h --';'~ anti-la ~'-: . . . . :,._a.. o-co. . . . . . . . . . . .s~a~t~ a ~ t ~ u o u y tO suppress n __,, development had defective T-cell proliferative responses that could be restored with antigen-specific B cells 8-1°. It is important to note, however, that several studies have shown that such B-cell deficient mice have normal levels of MHC class II restricted CD4 helper T cells n. Thus, these studies suggest that B cells are required for some but not all aspects of CD4 T-cell priming. Dendritic cells have been shown to be the most potent stimulators of CD4 T-cell responses to non-self MHC molecules 5, and as they constitutively express B7/BB112 and high levels of MHC class II molecules s, they are also excellent candidates for initiating CD4 T-cell responses to extrinsic antigens. However, DC are quite inefficient at antigen uptake and lack a means for discriminating between extrinsic protein antigens and self proteins whose peptides compete with them for presentation. As it is estimated that 100-200 MHC class II peptide complexes are required to signal a CD4 T cell, and as a DC has around 10 s MHC class II molecules, a maximum of 1000 peptides could be presented by such a cell. Moreover, direct evidence shows that some peptides are very much overexpressed on DC ~3, suggesting even less complexity. Thus, it seems likely that extrinsic antigens will be presented relatively inefficiently by DC, consistent with the very high protein doses required for effective presentation of peptides by the MHC class II molecules of DC 6. Thus, only those peptides that bind extremely well to the MHC class II alleles of the DC are likely to achieve levels on the cell surface sufficient to prime a helper CD4 T cell. This probably accounts for the phenomenon of immunodominant peptide epitopes in primary CD4 T-cell responses. Once helper CD4 T cells are primed to immunodominant peptides on DC, they will in turn activate specific antigen-binding B cells that internalize antigen 10 000-fold more efficiently than non-specific cell¢ 41~. When these antigen-binding B cells are activated by the primed antigen-specific helper T cells, they become competent to prime naive CD4 T cells. Because of the large amounts of protein internalized by the antigen-specific B cell, a much greater range of peptides from the original protein, or from proteins associated with it, can be presented to these naive CD4 T cells. Thus, the antigen that binds to the B cell can diversify the CD4 T-cell response. Recent studies from Eynon and Parker I~ and from Fuchs and Matzinger ~7 demonstrate that when resting B cells present antigen to CD4 T cells, tolerance resu!ts, an observation thought to reflect the absence of co-stimuiatory activity on resting B cells. By contrast, B cells activated with a variety of microbial substances can stimulate naive CD4 T-cell proliferative responses in vitro ~s, although Fuchs and Matzinger ~ find that even LPS-acti-