Comparative analysis of CD8 T cell response to cytomegalovirus or influenza virus in healthy human adults (P3002)

The competency of antigen specific (Ag+) lymphocytes plays a critical role in the adaptive immune response. However, little is known about the differences in the competency of Ag+ T cells against different viruses. Here, we compared the CD8 T cell responses of 23 healthy adults to CMV (pp65) or Flu (M1) peptides using an in vitro artificial antigen presenting system. We found that CD8 T cell responses to CMV or Flu varied in both proliferation and Granzyme B production and were independent of the frequency of initial CMV+ or Flu+ CD8 T cells. In the comparison of the responses of Naïve (Tn) and central memory (Tcm) CD8 T cells, Tcm exhibited a greater expansion than did Tn for both CMV and Flu antigen. Intriguingly, the variations of the expansion between CMV+ and Flu+ CD8 T cells were observed only in Tcm but not Tn cells, indicating the importance of antigen experience. Furthermore, the expansion ability was correlated with the telomere length in the initial CD8 T cells positively and expanded Ag+ CD8 T cells negatively, suggesting a role for telomere length in cell proliferation. Taken together, this study showed that incompetency of Ag+ CD8 T cells is associated with antigen experience and short telomere length in healthy adults. Currently, we are analyzing the usage of the TCR variable genes (alpha and beta) of CMV+ or Flu+ CD8 T cells by a single cell RT-PCR-Sequencing method to gain additional information about the structure of these TCR against CMV and Flu antigens.

Abstract 4531: Nanoscale Artificial Antigen Presenting Cells for T Cell Immunotherapy

Artificial antigen presenting cells (aAPC), which deliver stimulatory signals to cytotoxic lymphocytes, are a powerful tool for adoptive immunotherapy and in vivo T cell stimulation. Thus far, bead-based aAPC have been synthesized by coupling T cell activating proteins such as CD3 or MHC-peptide to beads several microns in diameter. By reducing the size of aAPC, we anticipated more efficient delivery of these stimulatory signals to tumor and lymph nodes where antigen-specific T cells reside. We thus manufactured aAPC based on two nanoscale particle platforms: biocompatible iron-dextran paramagnetic particles, 50-100 nm in diameter, and avidin-coated quantum dot nanocrystals, less than 20 nm in diameter. Nanoscale aAPC induced antigen-specific T cell proliferation from both TCR transgenic mouse splenocytes and human, polyclonal peripheral blood T cells. In a subcutaneous mouse melanoma model, both iron-dextran particles and quantum dot nanocrystals mediated tumor rejection when injected in vivo. To our knowledge, this is the first description of a nanoscale, particle-based aAPC that induces T cell proliferation in vitro and leads to effective T cell stimulation and tumor rejection in vivo. Furthermore, nano-aAPC represent a novel platform for studying receptor-ligand interactions at the membrane-nanoparticle interface.

Citation Format: Karlo Perica, Joan G. Bieler, Andrés De León Medero, Yen-Ling Chiu, Malarvizhi Durai, Michaela Niemöller, Mario Assenmacher, Anne Richter, Mathias Oelke, Jonathan Schneck. Nanoscale Artificial Antigen Presenting Cells for T Cell Immunotherapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4531. doi:10.1158/1538-7445.AM2013-4531

[Intraprostatic injection therapy in patients with benign prostatic syndrome]

Intraprostatic injection therapy is a minimally invasive treatment of patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia and could be a therapeutic alternative in increasingly older and co-morbid patients. Nowadays only botulinum neurotoxin A (BoNT/A), absolute ethanol, NX-1207 and PRX302 are of relevance but none of these substances has yet been authorized for treatment use (off-label use). There have been only three randomized, placebo-controlled trials (RCTs) for BoNT/A, whereas none exist for ethanol and the results of existing studies are inconsistent and without convincing proof of efficacy. NX-1207 is a protein with selective pro-apoptotic properties and non-inferiority compared to finasteride has been demonstrated. PRX302 is a modified proaerolysin that can be activated by prostate-specific antigen and is therefore (prostate) cell-specific. Safety and efficacy are well documented; however, intraprostatic injection therapy should presently only be performed in clinical trials, irrespective of the substance used.

T-cell memory responses elicited by yellow fever vaccine are targeted to overlapping epitopes containing multiple HLA-I and -II binding motifs

The yellow fever vaccines (YF-17D-204 and 17DD) are considered to be among the safest vaccines and the presence of neutralizing antibodies is correlated with protection, although other immune effector mechanisms are known to be involved. T-cell responses are known to play an important role modulating antibody production and the killing of infected cells. However, little is known about the repertoire of T-cell responses elicited by the YF-17DD vaccine in humans. In this report, a library of 653 partially overlapping 15-mer peptides covering the envelope (Env) and nonstructural (NS) proteins 1 to 5 of the vaccine was utilized to perform a comprehensive analysis of the virus-specific CD4(+) and CD8(+) T-cell responses. The T-cell responses were screened ex-vivo by IFN-γ ELISPOT assays using blood samples from 220 YF-17DD vaccinees collected two months to four years after immunization. Each peptide was tested in 75 to 208 separate individuals of the cohort. The screening identified sixteen immunodominant antigens that elicited activation of circulating memory T-cells in 10% to 33% of the individuals. Biochemical in-vitro binding assays and immunogenetic and immunogenicity studies indicated that each of the sixteen immunogenic 15-mer peptides contained two or more partially overlapping epitopes that could bind with high affinity to molecules of different HLAs. The prevalence of the immunogenicity of a peptide in the cohort was correlated with the diversity of HLA-II alleles that they could bind. These findings suggest that overlapping of HLA binding motifs within a peptide enhances its T-cell immunogenicity and the prevalence of the response in the population. In summary, the results suggests that in addition to factors of the innate immunity, "promiscuous" T-cell antigens might contribute to the high efficacy of the yellow fever vaccines.

Molecular identification of GD3 as a suppressor of the innate immune response in ovarian cancer

Tumors often display mechanisms to avoid or suppress immune recognition. One such mechanism is the shedding of gangliosides into the local tumor microenvironment, and a high concentration of circulating gangliosides is associated with poor prognosis. In this study, we identify ganglioside GD3, which was isolated from the polar lipid fraction of ovarian cancer-associated ascites, as an inhibitory factor that prevents innate immune activation of natural killer T (NKT) cells. Purified GD3 displayed a high affinity for both human and mouse CD1d, a molecule involved in the presentation of lipid antigens to T cells. Purified GD3, as well as substances within the ascites, bound to the CD1d antigenic-binding site and did not require additional processing for its inhibitory effect on NKT cells. Importantly, in vivo administration of GD3 inhibited α-galactosylceramide (α-GalCer)-induced NKT cell activation in a dose-dependent manner. These data therefore indicate that ovarian cancer tumors may use GD3 to inhibit the antitumor NKT cell response as an early mechanism of tumor immune evasion.

Detrusor underactivity: a plea for new approaches to a common bladder dysfunction

AIMS

Detrusor underactivity (DU) is defined by the International Continence Society as a contraction of reduced strength and/or duration resulting in prolonged or incomplete emptying of the bladder but has yet received only little attention. The purpose of this report is to summarize the ICI-RS meeting in Bristol in 2010 exploring current knowledge on DU and outline directions for future research.

METHODS

A think tank discussion was held and the summary of discussions was presented to all ICI-RS participants. This report is based on the final discussions.

RESULTS

The understanding of the pathophysiology, epidemiology, assessment, and treatment of DU remains rudimentary. DU is defined by pressure-flow analysis but no consensus exists regarding which of the available formulae should be used for quantification of detrusor work. DU is likely to be multifactorial. Aging causes a decay in detrusor activity but other concomitant causes, either myogenic or neurogenic, may aggravate the problem resulting in decrease of detrusor contractility. No effective pharmacotherapy for the condition exists. Only a few surgical therapeutic strategies have been explored, such as neuromodulation and skeletal muscle myoplasties. Consequently, the management of affected individuals remains unsatisfactory.

CONCLUSIONS

Future directions recommended by the ICI-RS panel include assessment of pathogenesis by developing novel animal models in addition to new non-invasive tests allowing longitudinal trials. Furthermore, optimizing the existing evaluation algorithms to support standard testing for DU and further epidemiological studies to quantify the size of the problem are required for the development of future treatment modalities.

Heat shock protein 70/peptide complexes: potent mediators for the generation of antiviral T cells particularly with regard to low precursor frequencies

Background

Heat shock protein 70 (HSP70) has gained major attention as an adjuvant capable of inducing antigen-specific CD8⁺ and CD4⁺ T-cell responses. The ability of HSP70/peptide complexes to elicit cytotoxic T-cell (CTL) responses by cross-presentation of exogenous antigens via HLA class I molecules is of central interest in immunotherapy. We examined the role of HSP70/CMVpp65_495-503-peptide complex (HSP70/CMV-PC) in HLA class I-restricted cross-presentation for ex vivo expansion of CMV-specific CTLs.

Methods

CMV-specific T cells generated from PBMCs of HLA-A*02:01/CMV-seropositive donors were stimulated for 21 days with HSP70/CMV-PC and analyzed in functional assays. As a control PBMCs were cultured in the presence of CMVpp65_495-503 peptide or HSP70. Increase of CMV-specific CTLs was visualized by pentameric HLA-A*02:01/CMVpp65_495-503 complex.

Results

About 90% of HSP70/CMV-PC generated T cells were CMV-specific and exhibited significantly higher IFN-γ secretion, cytotoxic activity, and an increased heme oxygenase 1 (HO-1) gene expression as compared to about 69% of those stimulated with CMVpp65_495-503 peptide. We decided to classify the HLA-A*02:01/CMV-seropositive donors as weak, medium, and strong responder according to the frequency of generated A2/CMV-pentamer-positive CD8⁺ T cells. HSP70/CMV-PC significantly induces strong antiviral T-cell responses especially in those donors with low memory precursor frequencies. Blockage of CD91 with α2-macroglobulin markedly reduced proliferation of antiviral T cells suggesting a major role of this receptor in the uptake of HSP70/CMV-PC.

Conclusion

This study clearly demonstrates that HSP70/CMV-PC is a potent mediator to induce stronger T-cell responses compared to antiviral peptides. This simple and efficient technique may help to generate significant quantities of antiviral CTLs by cross-presentation. Thus, we propose HSP70 for chaperoning peptides to reach an efficient level of cross-presentation. HSP70/peptide complexes may be particularly useful to generate stronger T-cell responses in cases of low precursor frequencies and may help to improve the efficiency of antigen-specific T-cell therapy for minor antigens.

Decline of influenza-specific CD8+ T cell repertoire in healthy geriatric donors

Background

While influenza vaccination results in protective antibodies against primary infections, clearance of infection is primarily mediated through CD8⁺ T cells. Studying the CD8⁺ T cell response to influenza epitopes is crucial in understanding the disease associated morbidity and mortality especially in at risk populations such as the elderly. We compared the CD8⁺ T cell response to immunodominant and subdominant influenza epitopes in HLA-A2⁺ control, adult donors, aged 21-42, and in geriatric donors, aged 65 and older.

Results

We used a novel artificial Antigen Presenting Cell (aAPC) based stimulation assay to reveal responses that could not be detected by enzyme-linked immunosorbent spot (ELISpot). 14 younger control donors and 12 geriatric donors were enrolled in this study. The mean number of influenza-specific subdominant epitopes per control donor detected by ELISpot was only 1.4 while the mean detected by aAPC assay was 3.3 (p = 0.0096). Using the aAPC assay, 92% of the control donors responded to at least one subdominant epitopes, while 71% of control donors responded to more than one subdominant influenza-specific response. 66% of geriatric donors lacked a subdominant influenza-specific response and 33% of geriatric donors responded to only 1 subdominant epitope. The difference in subdominant response between age groups is statistically significant (p = 0.0003).

Conclusion

Geriatric donors lacked the broad, multi-specific response to subdominant epitopes seen in the control donors. Thus, we conclude that aging leads to a decrease in the subdominant influenza-specific CTL responses which may contribute to the increased morbidity and mortality in older individuals.

Expression and distribution of key enzymes of the cyclic GMP signaling in the human clitoris: relation to phosphodiesterase type 5 (PDE5)

The clitoris contributes to the normal female sexual response cycle. A significance of cyclic guanosine monophosphate (GMP) has been assumed in the control of clitoral vascular smooth muscle. As only a few investigations on the physiology of the vascular and non-vascular clitoral tissue have been carried out, knowledge on the mechanisms controlling this particular female genital organ is still vague. It has been suggested that human clitoral corpus cavernosum smooth muscle is regulated by nitric oxide (NO)/cyclic GMP and related key enzymes, such as NO synthases (NOSs) and the phosphodiesterase type 5 (PDE5). The present study evaluated in the human clitoris, by means of immunohistochemistry, the expression and distribution of key enzymes of the cyclic GMP pathway, such as the endothelial NOS, PDE2, PDE11 and cyclic GMP-dependent protein kinase type I (cGKI) in relation to the PDE5. Immunohistochemistry revealed the presence of PDE2, PDE5 and cGKI in the smooth muscle wall of blood vessels transversing the supepithelial and stromal space. Immunosignals specific for PDE2 were also identified in interstitial-like cells located in the basal epithelial layer. Staining for PDE11A was observed in single nerve trunks located in the clitoral stroma. The results are in favor of a role of the cyclic GMP signaling in the control of clitoral blood flow. It seems likely that PDE2 and PDE11 are also involved in the mechanism of local (neuro)transmission in the clitoris.

[Latest trends and recommendations on epidemiology, diagnosis, and treatment of benign prostatic hyperplasia (BPH)]

BACKGROUND

A re-evaluation of established tests and treatments has become necessary after publication of several new guidelines on BPH during the past two years. This article describes the latest developments concerning epidemiology, diagnosis, and treatment of BPH.

MATERIAL AND METHODS

Diagnostic and treatment guidelines on BPH of the German, European, or North American urologists as well as UK doctors were reviewed according to key articles and latest modifications.

RESULTS

The only German epidemiological trial on BPH demonstrated that all components of the BPH disease (symptoms - prostate enlargement - bladder outlet obstruction) increase with ageing. 27 % of German men will have disease progression within the next 5 years. Risk factors for disease progression are: age, symptoms, prostate size, PSA, urinary flow rate, and postvoiding residual urine. Diagnosis aims to distinguish BPH from other diseases with similar symptoms, quantify the BPH components, and estimate the individual risk of disease progression. BPH is an exclusion diagnosis. Ultrasonic measurement of detrusor wall thickness at the anterior wall of bladders filled with ≥ 250 mL can securely detect bladder outlet obstruction if the value is ≥ 2 mm. Watchful waiting and lifestyle modifications are suitable for men with mild symptoms and low disease progression risk. All drugs used in BPH treatment reduce symptoms but have no influence on bladder outlet obstruction. α-blockers are first-line drugs and may be combined with muscarinic receptor antagonists or 5α-reductase inhibitors to further increase efficacy. Prostate surgery is indicated when drug treatment is insufficient, the patient develops complications in the upper or lower urinary tract (absolute indications), or has severe bladder outlet obstruction. Standard operations are TURP in small (≤ 80 mL) or open prostatectomy in large prostates (> 80 mL). Minimally invasive, alter-native surgeries may be considered in selected men and -offer advantages with regard to the risk of bleeding, duration of catheterisation, or maintenance of sexual function.

CONCLUSIONS

Current guidelines have integrated the latest knowledge and developments on BPH and are likely to improve assessment and treatment.

HLA-Ig based artificial antigen presenting cells for efficient ex vivo expansion of human CTL

CTL with optimal effector function play critical roles in mediating protection against various intracellular infections and cancer. However, individuals may exhibit suppressive immune microenvironment and, in contrast to activating CTL, their autologous antigen presenting cells may tend to tolerize or anergize antigen specific CTL. As a result, although still in the experimental phase, CTL-based adoptive immunotherapy has evolved to become a promising treatment for various diseases such as cancer and virus infections. In initial experiments ex vivo expanded CMV (cytomegalovirus) specific CTL have been used for treatment of CMV infection in immunocompromised allogeneic bone marrow transplant patients. While it is common to have life-threatening CMV viremia in these patients, none of the patients receiving expanded CTL develop CMV related illness, implying the anti-CMV immunity is established by the adoptively transferred CTL¹. Promising results have also been observed for melanoma and may be extended to other types of cancer².

While there are many ways to ex vivo stimulate and expand human CTL, current approaches are restricted by the cost and technical limitations. For example, the current gold standard is based on the use of autologous DC. This requires each patient to donate a significant number of leukocytes and is also very expensive and laborious. Moreover, detailed in vitro characterization of DC expanded CTL has revealed that these have only suboptimal effector function ³.

Here we present a highly efficient aAPC based system for ex vivo expansion of human CMV specific CTL for adoptive immunotherapy (Figure 1). The aAPC were made by coupling cell sized magnetic beads with human HLA-A2-Ig dimer and anti-CD28mAb⁴. Once aAPC are made, they can be loaded with various peptides of interest, and remain functional for months. In this report, aAPC were loaded with a dominant peptide from CMV, pp65 (NLVPMVATV). After culturing purified human CD8⁺ CTL from a healthy donor with aAPC for one week, CMV specific CTL can be increased dramatically in specificity up to 98% (Figure 2) and amplified more than 10,000 fold. If more CMV-specific CTL are required, further expansion can be easily achieved by repetitive stimulation with aAPC. Phenotypic and functional characterization shows these expanded cells have an effector-memory phenotype and make significant amounts of both TNFα and IFNγ (Figure 3).

Killer artificial antigen-presenting cells: the synthetic embodiment of a 'guided missile'

At present, the treatment of T-cell-dependent autoimmune diseases relies exclusively on strategies leading to nonspecific suppression of the immune systems causing a substantial reduced ability to control concomitant infections or malignancies. Furthermore, long-term treatment with most drugs is accompanied by several serious adverse effects and does not consequently result in cure of the primary immunological malfunction. By contrast, antigen-specific immunotherapy offers the potential to achieve the highest therapeutic efficiency in accordance with minimal adverse effects. Therefore, several studies have been performed utilizing antigen-presenting cells specifically engineered to deplete allo- or antigen-specific T cells ('guided missiles'). Many of these strategies take advantage of the Fas/Fas ligand signaling pathway to efficiently induce antigen-presenting cell-mediated apoptosis in targeted T cells. In this article, we discuss the advantages and shortcomings of a novel non-cell-based 'killer artificial antigen-presenting cell' strategy, developed to overcome obstacles related to current cell-based approaches for the treatment of T-cell-mediated autoimmunity.

Novel cellular microarray assay for profiling T-cell peptide antigen specificities

We present a novel cellular microarray assay using soluble peptide-loaded HLA A2-Ig dimer complexes that optimizes the avidity of peptide-HLA binding by preserving the molecular flexibility of the dimer complex while attaining much higher concentrations of the complex relative to cognate T-cell receptors. A seminal advance in assay development is made by separating the molecular T-cell receptor recognition event from the binding interactions that lead to antigen-specific cell capture on the microarray. This advance enables the quantitative determination of antigen-specific frequencies in heterogeneous T-cell populations without enumerating the number of cells captured on the microarray. The specificity of cell capture, sensitivity to low antigen-specific frequencies, and quantitation of antigenic T-cell specificities are established using CD8 T-cell populations with prepared antigen-specific CTL frequencies and heterogeneous T cells isolated from peripheral blood. The results demonstrate several advantages for high-throughput broad-based, quantitative assessments of low-frequency antigen specificities. The assay enables the use of cellular microarrays to determine the stability and flux of antigen-specific T-cell responses within and across populations.

Overview of a HLA-Ig based "Lego-like system" for T cell monitoring, modulation and expansion

Recent advances in molecular medicine have shown that soluble MHC-multimers can be valuable tools for both analysis and modulation of antigen-specific immune responses in vitro and in vivo. In this review, we describe the use of dimeric human and mouse major histocompatibility complexes, MHC-Ig, as part of an artificial Antigen-Presenting Cell (aAPC). MHC-Ig-based aAPC and its derivatives represent an exciting new platform technology for measuring and manipulating immune responses in vitro as well as in vivo. This new technology has the potential to help overcome many of the obstacles associated with limitations in current antigen-specific approaches of immunotherapy for the treatment of cancer, infectious diseases and autoimmunity.

Costimulatory signals regulate the proliferative potential and effector function of NKT cells (95.14)

Natural killer T (NKT) cells play a pivotal role in maintaining immune homeostasis. NKT cells rapidly secrete both proinflammatory and inflammatory cytokines following activation. However, the role costimulatory molecules during activation and their impact on effector functions have yet to be clearly defined. Our innovative system, which utilizes bead-based artificial Antigen Presenting Cells (aAPC), allows us to systematically evaluate the role of different costimulatory molecules on NKT cell activation and expansion. In this study, we have examined the effects of CD28, CD44, CD161, and OX-40 on NKT cell proliferation, phenotype and function. We found that the costimulatory molecules which increased NKT cell proliferation also enhanced cytokine production and cytotoxic function. These studies will enhance our knowledge of NKT cell biology and may aid in the development of novel NKT cell-based immunotherapeutic approaches for the treatment of infectious and autoimmune diseases, as well as cancer.

Identification of an inhibitory ganglioside responsible for immune suppressive effects associated with ovarian cancer (100.27)

Tumors often use mechanisms to prevent or suppress immune recognition. One such mechanism is the shedding of immune-suppressive glycolipids into the local microenvironment. Previously we reported that pretreatment of CD1d expressing stimulator cells with ascites fluid from ovarian cancer patients inhibited the activation of NKT cells, one of the earliest lines of defense in an anti-cancer immune response. Here we identify the inhibitory factor responsible, ganglioside GD3, which we isolated from the polar lipid fraction of ovarian cancer-associated ascites. GD3 inhibited CD1d-mediated NKT cell activation directly, without antigen processing. Purified GD3 binds with high affinity to CD1d, even when compared to the well-established experimental CD1d activator, α-galactosylceramide. Mechanistically we show that factors in ascites fluid as well as purified GD3 bind directly to the CD1 antigenic binding site, and this presumably displaces endogenous NKT cell ligands. These data indicate that shedding of GD3 by ovarian cancer tumors is a mechanism of immune evasion that inhibits the activation of an anti-tumor NKT cell response.

In vivo administration of artificial Antigen Presenting Cells licenses low avidity T cells for treatment of cancer (131.13)

The development of effective anti-tumor immune responses is normally constrained by low avidity, tumor-specific cytotoxic T lymphocytes (CTL) which are unable to eradicate the tumor. Therefore, new strategies to rescue anti-tumor activity of low avidity melanoma-specific CTL in vivo may improve immunotherapy efficacy. To boost the in vivo effectiveness of low avidity CTL we immunized mice bearing metastatic lung melanoma with artificial Antigen Presenting Cells (aAPC), made by covalently coupling pepMHC-Ig dimers and B7.1-Ig molecules to magnetic beads. aAPC treatment induced significant tumor reduction in a mouse telomerase antigen system and complete tumor eradication in a mouse TRP-2 antigen system, when low avidity CTL specific for these antigens were adoptively transferred. In addition, in an in vivo treatment model of subcutaneous melanoma, aAPC injection also augmented the activity of adoptively transferred CTL and significantly delayed tumor growth. In vivo tumor clearance due to aAPC administration correlated with in situ proliferation of the transferred CTL. In vitro studies showed that aAPC effectively stimulated cytokine release and TCR down-regulation in low avidity CTL. Therefore, in vivo aAPC administration represents a potentially novel approach to improve adoptive immunotherapy of cancer.

Interleukin-2 significantly upregulates CD86 expression on T cells during cytokine therapy (131.35)

Interleukin-2 (IL-2) is one of the most widely used cytokines in therapeutic applications, and its efficacy in the treatment of various cancers and chronic viral infections has been extensively tested. Several studies have focused on the impact of IL-2 on T-cell survival and proliferation. However, very few have focused on IL-2-induced phenotypic changes in T cells, although this is particularly relevant to cytokine therapy. To gain insight into this issue, we analyzed blood samples from patients receiving IL-2 therapy in order to elucidate the phenotype changes occurring in their T cells. A key finding was a marked increase in CD86 expression on CD4+ and CD8+ T cells. Detailed characterizations of the corresponding cytokine-induced CD86 expression profiles on T cells were obtained in subsequent in vitro experiments. We found that the IL-2-induced CD86 molecules are unable to provide costimulatory signals to antigen-specific T cells during activation. Moreover while these CD86 molecules shown to have no binding affinity for CD28 molecules, their binding affinity for the inhibitory molecule CTLA-4 remained intact. Therefore, it is likely that the IL-2-induced CD86 expression on T cells have a modulatory role on IL-2-induced inflammatory response and its related side effects.

Decline of influenza-specific T cell repertoire in healthy geriatric donors (85.2)

While the goal of influenza vaccination is to develop antibodies to protect against a primary infection, clearance of the infection is primarily mediated through CD8+ T cells. The study of the CD8+ T cell response to influenza epitopes is crucial in understanding the disease and associated morbidity and mortality. The age-associated decline of the immune system is believed to be responsible for the increased risk of influenza infection in the geriatric population. Since the CTL response is important for the clearance of influenza infection, we compared the CTL response to immunodominant and subdominant influenza epitopes in HLA-A2+ control adult donors, aged 21-42, to the response in healthy geriatric donors, aged 65 and older. This was done using an artificial Antigen Presenting Cell (aAPC) based stimulation assay which revealed responses that could not be detected by ELISpot. Control donors showed a broad, multi-specific response to the subdominant epitopes, and each donor’s subdominant influenza-specific response was unique. When comparing the control donors’ CTL response to the geriatric donors’, the immunodominant M1 responses were preserved, however, the geriatric donors lacked the broad multi-specific response to influenza-specific subdominant epitopes seen in the control donors. These data indicate that aging leads to a decrease in the subdominant influenza-specific CTL responses which may contribute to the increased morbidity and mortality in older individuals.