Proteomic Signature of HIV-Associated Subclinical Left Atrial Remodeling and Incident Heart Failure.

Background: People living with HIV (PLWH) are at higher risk of heart failure (HF) and preceding subclinical cardiac abnormalities, including left atrial dilation, compared to people without HIV (PWOH). Hypothesized mechanisms include premature aging linked to chronic immune activation. We leveraged plasma proteomics to identify potential novel contributors to HIV-associated differences in indexed left atrial volume (LAVi) among PLWH and PWOH and externally validated identified proteomic signatures with incident HF among a cohort of older PWOH. Methods: We performed proteomics (Olink Explore 3072) on plasma obtained concurrently with cardiac magnetic resonance imaging among PLWH and PWOH in the United States. Proteins were analyzed individually and as agnostically defined clusters. Cross-sectional associations with HIV and LAVi were estimated using multivariable regression with robust variance. Among an independent general population cohort, we estimated associations between identified signatures and LAVi using linear regression and incident HF using Cox regression. Results: Among 352 participants (age 55±6 years; 25% female), 61% were PLWH (88% on ART; 73% with undetectable HIV RNA) and mean LAVi was 29±9 mL/m 2 . Of 2594 analyzed proteins, 439 were associated with HIV serostatus, independent of demographics, hepatitis C virus infection, renal function, and substance use (FDR<0.05). We identified 73 of these proteins as candidate contributors to the independent association between positive HIV serostatus and higher LAVi, enriched in tumor necrosis factor (TNF) signaling and immune checkpoint proteins regulating T cell, B cell, and NK cell activation. We identified one protein cluster associated with LAVi and HIV regardless of HIV viral suppression status, which comprised 42 proteins enriched in TNF signaling, ephrin signaling, and extracellular matrix (ECM) organization. This protein cluster and 30 of 73 individual proteins were associated with incident HF among 2273 older PWOH (age 68±9 years; 52% female; 8.5±1.4 years of follow-up). Conclusion: Proteomic signatures that may contribute to HIV-associated LA remodeling were enriched in immune checkpoint proteins, cytokine signaling, and ECM organization. These signatures were also associated with incident HF among older PWOH, suggesting specific markers of chronic immune activation, systemic inflammation, and fibrosis may identify shared pathways in HIV and aging that contribute to risk of HF.

Changes in Inflammatory Cytokines After Chronic Hepatitis C Treatment Among People Living With HIV.

We aimed to evaluate the effect of hepatitis C virus cure on serum inflammatory markers among people with HIV. Among 127 people with HIV, serum alanine aminotransferase, soluble tumor necrosis factor receptor 1, and inflammatory index score were significantly lower at the 24-week time point in patients who achieved sustained virologic response as compared with those who did not.

A step-by-step guide to ileoanal J-pouch MRI interpretation.

BACKGROUND: Multidisciplinary management of patients with an ileoanal pouch requires dedicated imaging to identify structural problems of the pouch associated with dysfunction. The purpose of this study is to provide a framework for interpretation of magnetic resonance imaging (MRI) scan of the ileoanal pouch to enable surgeons and radiologists to work cohesively, optimise diagnosis and ultimately improve patient care. METHODS: We propose a protocol for structured MRI assessment of the ileal pouch, aiming to provide surgeons a systematic report of the anatomy, its variations and pouch complications. This guide consists of studying the characteristics of the bowel, mesentery and anal canal. RESULTS: The presented checklist is designed to systematically interpret and identify abnormalities of the ileoanal pouch on MRI. It focuses on the characteristics of the bowel (encompassing pre-pouch ileum, pouch and rectal cuff), mesentery and anal canal. The different elements of the checklist are presented in the associated supplementary video. CONCLUSIONS: A combination of clinical assessment, endoscopic evaluations and imaging is fundamental to achieving accurate diagnosis of ileoanal pouch surgery complications and pouch dysfunction.

Coronary artery endothelial function and aging in people with HIV and HIV-negative individuals.

Coronary artery disease (CAD) is a common comorbidity in people with human immunodeficiency virus (HIV) (PWH) and impaired coronary endothelial function (CEF) plays a central role in the pathogenesis of CAD. Age-related impaired CEF among PWH, however, is not well characterized. We investigated the association between CEF and age in males and females with and without HIV using 3-T magnetic resonance imaging (MRI). We measured the changes in coronary cross-sectional area (CSA) and coronary blood flow during isometric handgrip exercise (IHE), an established endothelial-dependent stressor with smaller increases in CSA and coronary blood flow indicative of impaired CEF. We included 106 PWH and 82 individuals without HIV. Differences in demographic and clinical characteristics between PWH and individuals without HIV were explored using Pearson's χ2 test for categorical variables and Welch's t test for continuous variables. Linear regression models were used to examine the association between CEF and age. CEF was significantly lower in PWH as compared with individuals without HIV. Coronary endothelial dysfunction was also present at younger ages in PWH than in the individuals without HIV and there were significant differences in CEF between the PWH and individuals without HIV across age groups. Among the individuals without HIV, the percent changes in CSA were inversely related to age in unadjusted and adjusted models. There was no significant association between CEF and age in PWH. To the best of our knowledge, this is the first study to examine the relationship between age and CEF in PWH, and our results suggest that factors other than age significantly impair CEF in PWH across the life span.NEW & NOTEWORTHY This is the first study to examine the relationship between age and coronary endothelial function (CEF) in people with human immunodeficiency virus (HIV) (PWH). CEF was assessed using magnetic resonance imaging (MRI) in people with and without HIV. Although age and CEF were significantly inversely related in individuals without HIV, there was no association between age and CEF in PWH.

Circulating biomarker correlates of left atrial size and myocardial extracellular volume fraction among persons living with and without HIV.

BACKGROUND: Infection with human immunodeficiency virus (HIV) is associated with higher risk for myocardial disease despite modern combination antiretroviral therapy (cART). Factors contributing to this excess risk, however, remain poorly characterized. We aimed to assess cross-sectional relationships between elevations of left atrial volume index (LAVI) and myocardial extracellular volume (ECV) fraction that have been reported in persons living with HIV and levels of circulating biomarkers of inflammation, fibrosis, and myocyte stretch among persons living with and without HIV (PLWH, PLWOH). METHODS: Participants from three cohorts of PLWH and PLWOH underwent cardiovascular magnetic resonance imaging for measurement of LAVI and ECV. Levels of circulating proteins (IL-6, sCD14, galectin-3, NT-proBNP, GDF-15, TIMP-2, MMP-2, and hsTnI) were measured using immunoassays. Associations were assessed using logistic and linear regression, adjusting for demographics, substance use, and clinical characteristics. RESULTS: Among 381 participants with and without HIV, median age (IQR) was 55.1 (51.2, 58.4) years, 28% were female, 69% were Black, and 46% were current smokers. Sixty-two percent were PLWH (n = 235), of whom 88% were receiving cART and 72% were virally suppressed. PLWH had higher levels of sCD14 (p = < 0.001), GDF-15 (p = < 0.001), and NT-proBNP (p = 0.03) compared to PLWOH, while levels of other biomarkers did not differ by HIV serostatus, including IL-6 (p = 0.84). Among PLWH, higher sCD14, GDF-15, and NT-proBNP were also associated with lower CD4 + cell count, and higher NT-proBNP was associated with detectable HIV viral load. NT-proBNP was associated with elevated LAVI (OR: 1.79 [95% CI: 1.31, 2.44]; p < 0.001) with no evidence of effect measure modification by HIV serostatus. Other associations between HIV-associated biomarkers and LAVI or ECV were small or imprecise. CONCLUSIONS: Our findings suggest that elevated levels of sCD14, GDF-15, and NT-proBNP among PLWH compared to PLWOH observed in the current cART era may only minimally reflect HIV-associated elevations in LAVI and ECV. Future studies of excess risk of myocardial disease among contemporary cohorts of PLWH should investigate mechanisms other than those connoted by the studied biomarkers.

Frailty transitions, inflammation, and mortality among persons aging with HIV infection and injection drug use.

OBJECTIVE: Frailty is a critical aging-related syndrome marked by diminished physiologic reserve and heightened vulnerability to stress, predictive of major adverse clinical outcomes in HIV-infected and uninfected adults. Frailty is a dynamic state, yet little data exist on predictors and consequences of frailty transitions. DESIGN/METHODS: Frailty was assessed semiannually among HIV-infected and uninfected persons with prior injection drug use using the five Fried phenotype domains. An inflammatory index score was constructed from IL-6 and soluble TNF-α receptor-1 data. Markov transition models assessed determinants of frailty transitions. Cox proportional hazards models estimated mortality risk. RESULTS: Among 1353 AIDS Linked to the IntraVenous Experience participants with 9559 frailty transition assessments, 33% were HIV-infected. Younger age, higher education, employment, reduced comorbidity, HIV virologic suppression, elevated CD4 nadir (>500 cells/µl) and absence of a prior AIDS diagnosis were significantly associated with both reduced frailty progression and greater frailty recovery. Each SD decrease in inflammatory index score was associated with decreased frailty progression [odds ratio 0.78; 95% confidence interval (CI), 0.65, 0.92] and increased frailty recovery (odds ratio 1.29; 95% CI, 1.08, 1.53). Being frail at one of two consecutive visits was associated with increased mortality, compared with maintenance of a nonfrail state. Being frail at both of two consecutive visits demonstrated the highest mortality risk (hazard ratio 3.23; 95% CI, 2.1, 4.96). CONCLUSION: Sustained, and to a lesser degree, intermittent frail states are associated with increased mortality. HIV virologic suppression with earlier antiretroviral therapy, reduced comorbidity, and reduced inflammation may prevent frailty progression and promote frailty recovery, consequently improving survival for persons aging with HIV and persons with prior injection drug use.

Reducing injection intensity is associated with decreased risk for invasive bacterial infection among high-frequency injection drug users.

BACKGROUND: Bacterial infection is a major cause of morbidity and mortality for persons who inject drugs (PWID). Injection cessation may help abrogate such infections, but maintaining complete cessation is challenging. Limited data exists on the role of reduced injection intensity on invasive bacterial infection risk. We sought to evaluate decreased risk for bacterial infections following cessation and substantive reduction in the injection intensity. METHODS: Participants were persons in the AIDS Linked to the Intravenous Experience (ALIVE) cohort with initial high-frequency injection drug use (> 1 daily). Pooled logistic regression with generalized estimating equations was used to estimate risk for invasive bacterial infection (pneumonia, endocarditis, or sepsis) among participants achieving complete injection cessation or reduced injection intensity relative to those with sustained high-frequency use. RESULTS: Of 2247 study participants with 12,469 paired study visits, complete injection cessation was achieved at 13.5% and reduced injection intensity at 25.5% of study visits. Adjusting for sociodemographics and HIV status, injection cessation was associated with a 54% reduction of bacterial infection at 3 months (odds ratio [OR] 0.46, 95% CI 0.25-0.84) and a 46% reduction at 6 months (OR 0.54, 95% CI 0.36-0.81). Reduced injection intensity was associated with a 36% reduction of infection at 3 months (OR 0.64, 95% CI 0.43-0.96) and a 26% reduction at 6 months (OR 0.74, 95% CI 0.56-0.98). CONCLUSIONS: Both complete cessation and reduced injection frequency demonstrate substantial benefit in reducing invasive bacterial infection risk among PWID. With high rates of relapse into injection use, targeting sustained reductions in drug use intensity may be a key harm reduction modality for improving clinical outcomes in this population.

Inflammation Strikes Again: Frailty and HIV.

PURPOSE OF REVIEW: As a consequence of antiretroviral therapy, the proportion of older HIV-infected adults is increasing, with a concomitant shift in burden of illness to age-related syndromes and disease. Frailty is an age-related syndrome of increased vulnerability to stress, predictive of major adverse clinical outcomes among HIV-infected and uninfected persons alike. Understanding frailty pathogenesis is critical to developing interventions to improve health outcomes in HIV. Here, we review the current evidence for the relationship between inflammation and frailty in HIV, and the potential for novel, inflammation-targeted interventions. RECENT FINDINGS: Dysregulated inflammation has been consistently associated with frailty in elderly HIV-uninfected persons. Dysregulated inflammation is also central to HIV pathophysiology and several recent studies have demonstrated the important association of inflammation with frailty in HIV. Some evidence suggests that anti-inflammatory therapies may be effective in ameliorating the adverse impact of frailty among aging HIV-infected adults, though further investigation is necessary. Inflammation has been implicated in frailty in HIV infection, and improved understanding of the role that inflammation plays in frailty pathogenesis is key to the development of effective therapies to slow or prevent frailty in the vulnerable HIV-infected population.

Differential Relationships among Circulating Inflammatory and Immune Activation Biomediators and Impact of Aging and Human Immunodeficiency Virus Infection in a Cohort of Injection Drug Users.

As individuals with human immunodeficiency virus (HIV) infection live longer, aging and age-related chronic conditions have become major health concerns for this vulnerable population. Substantial evidence suggests that chronic inflammation and immune activation contribute significantly to chronic conditions in people aging with or without HIV infection. As a result, increasing numbers of inflammation and immune activation biomediators have been measured. While very few studies describe their in vivo relationships, such studies can serve as an important and necessary initial step toward delineating the complex network of chronic inflammation and immune activation. In this study, we evaluated in vivo relationships between serum levels of neopterin, a biomediator of immune activation, and four commonly described inflammatory biomediators: soluble tumor necrosis factor (TNF)-α receptor (sTNFR)-1, sTNFR-2, interleukin (IL)-6, and C-reactive protein (CRP), as well as the impact of HIV infection and aging in the AIDS Linked to the Intravenous Experience (ALIVE) study, a community-recruited observational study of former and current injection drug users (IDUs) with or at high risk for HIV infection in Baltimore, MD, USA. The study included 1,178 participants in total with 316 HIV-infected (HV+) and 862 HIV-uninfected (HIV-) IDUs. Multivariate regression analyses were employed, adjusting for age, sex, body mass index, smoking, hepatitis C virus co-infection, injection drug use, comorbidities, and HIV status (for all participants), and HIV viral load, CD4+ T-cell counts, and antiretroviral therapy (for HIV+ participants). The results showed significant impact of aging on all five biomediators and that of HIV infection on all but sTNFR-1. In the adjusted model, neopterin had positive associations with sTNFR-1 and sTNFR-2 (partial correlation coefficients: 0.269 and 0.422, respectively, for all participants; 0.292 and 0.354 for HIV+; and 0.262 and 0.435 for HIV-, all p < 0.0001). No significant associations between neopterin and IL-6 or CRP were identified. Such differential relationships between circulating neopterin and sTNFR-1, sTNFR-2, IL-6, and CRP may help inform their selection in future studies. These findings may also facilitate elucidation of underlying inflammatory and immune activation pathways that contribute to age-related chronic conditions, potentially leading to identification of key biomediators, particularly those upstream of CRP, as novel targets for intervention.

Role of Suppressive Oral Antibiotics in Orthopedic Hardware Infections for Those Not Undergoing Two-Stage Replacement Surgery.

Background. The use of suppressive antibiotics in treatment of orthopedic hardware infections (OHIs), including spinal hardware infections, prosthetic joint infections, and infections of internal fixation devices, is controversial. Methods. Over a 4-year period at 2 academic medical centers, patients with OHI who were treated with debridement and retention of hardware components, with single-stage exchange, or without surgery were studied to determine whether use of oral antibiotics for at least 6 months after diagnosis impacts successful treatment of the infection at 1 year after diagnosis. Results. Of 89 patients in the study, 42 (47.2%) were free of clinical infection 1 year after initial diagnosis. Suppressive antibiotics used for at least 6 months after diagnosis was not associated with being free of clinical infection (adjusted odds ratio [aOR], 5.29; 95% confidence interval [CI], .74-37.80), but being on suppressive antibiotics at least 3 months after diagnosis was associated with being free of clinical infection (OR, 3.50; 95% CI, 1.30-9.43). Causative organisms impacted the likelihood of success; patients with methicillin-resistant Staphylococcus aureus as well as with Gram-negative rods were both less likely to have achieved clinical success at 1 year after surgery (aOR = 0.018, 95% CI = .0017-.19 and aOR = 0.20, 95% CI = .039-.99, respectively). Conclusions. Oral suppressive antibiotic therapy in treatment of OHI with retention of hardware for 3 months, but not 6 months, postdiagnosis increases the likelihood of treatment success. The organisms implicated in the infection directly impact the likelihood of treatment success.

Nontyphoidal Salmonellosis, Human Immunodeficiency Virus Infection, and Ischemic Stroke.

Nontyphoidal Salmonella infection and stroke are major causes of morbidity and mortality worldwide, with increased risk in the human immunodeficiency virus (HIV)-infected population. We report a rare case of ischemic stroke associated with Salmonella enteritidis subdural empyema in an older HIV-infected patient with multimorbidity, despite surgery and treatment with susceptible antimicrobial drugs.

Frailty, Inflammation, and Mortality Among Persons Aging With HIV Infection and Injection Drug Use.

BACKGROUND: Serum markers of inflammation increase with age and have been strongly associated with adverse clinical outcomes among both HIV-infected and uninfected adults. Yet, limited data exist on the predictive and clinical utility of aggregate measures of inflammation. This study sought to evaluate the relationship of a recently validated aggregate inflammatory index with frailty and mortality among aging HIV-infected and uninfected injection drug users. METHODS: Frailty was assessed among HIV-infected and uninfected participants in the AIDS Linked to the IntraVenous Experience (ALIVE) cohort study using the five Fried phenotypic criteria: weight loss, exhaustion, low physical activity, decreased grip strength, and slow gait. The aggregate inflammatory index was constructed from serum measures of interleukin-6 and soluble tumor necrosis factor-α receptor-1. Multinomial logistic regression was used to assess the relationship of frailty with inflammation. Cox proportional hazards models were used to estimate risk for all-cause mortality. RESULTS: Among 1,326 subjects, the median age was 48 years and 29% were HIV-infected. Adjusting for sociodemographics, comorbidity, and HIV status, frailty was significantly associated with each standard deviation increase in log interleukin-6 (odds ratio 1.33; 95% CI, 1.09-1.61), log tumor necrosis factor-α receptor-1 (odds ratio 1.25; 95% CI, 1.04-1.51) and inflammatory index score (odds ratio 1.39; 95% CI, 1.14-1.68). Adjusting for sociodemographics, comorbidity, HIV status, and frailty, the inflammatory index score was independently associated with increased mortality (HR 1.65; 95% CI, 1.44-1.89). CONCLUSION: A recently validated, simple, biologically informed inflammatory index is independently associated with frailty and mortality risk among aging HIV-infected and uninfected injection drug users.

COMPARISON OF OPERATIVE TIME AND LENGTH OF HOSPITAL STAY IN LAPAROSCOPIC CHOLECYSTECTOMY IN ACUTE VERSES CHRONIC CHOLECYSTITIS.

BACKGROUND: The laparoscopic surgery has opened a new era in the field of surgery. Currently, it is accepted as the "gold standard" in the treatment of symptomatic cholelithiasis. However, laparoscopic cholecystectomy (LC) performed for acute cholecystitis is technically difficult because of severe inflammatory adhesions and distortion of the biliary anatomy. The objective of this study was to compare the frequency, mean operative time and length of hospital stay in patients of acute and chronic cholecystitis undergoing laparoscopic cholecystectomy. METHODS: This prospective comparative study was carried out in the department of General Surgery Jinnah Postgraduate Medical Centre (JPMC) Karachi, from March to September 2013. During this period 233 patients underwent laparoscopic cholecystectomy (54 cases of acute and 179 cases of chronic cholecystitis respectively). The patients who were pregnant, diagnosed with gall bladder mass on ultrasound, carcinoma gall bladder, acute pancreatitis, and those with comorbid like diabetes mellitus/cardiovascular disorders were excluded. RESULT: A total of 233 patients were admitted for laparoscopic cholecystectomy. Fifty four (54) patients in Group A (acute cholecystitis) and 179 patients in Group B (chronic cholecystitis) with female: male 2.8:1 and 4:1 in Group A and B respectively. Operative time was longer for group A. Six cases of conversion to open procedure one (1) in Group A and 5 in Group B respectively. CONCLUSION: Laparoscopic cholecystectomy is safe and efficient for both acute and chronic cholecystitis.

MyD88-dependent induction of allergic Th2 responses to intranasal antigen.

MyD88 is a common Toll-like receptor (TLR) adaptor molecule found to be essential for induction of adaptive Th1 immunity. Conversely, innate control of adaptive Th2 immunity has been shown to occur in a MyD88-independent manner. In this study, we show that MyD88 is an essential innate component in the induction of TLR4-dependent Th2 responses to intranasal antigen; thus we demonstrate what we believe to be a novel role for MyD88 in pulmonary Th2 immunity. Induction of the MyD88-independent type I IFN response to LPS is defective in the pulmonary environment. Moreover, in the absence of MyD88, LPS-induced upregulation of costimulatory molecule expression on pulmonary DCs is defective, in contrast to what has been observed with bone marrow-derived DCs (BMDCs). Reconstitution of Th2 responses occurs upon adoptive pulmonary transfer of activated BMDCs to MyD88-deficient recipients. Furthermore, the dependence of Th2 responses on MyD88 is governed by the initial route of antigen exposure; this demonstrates what we believe are novel site-specific innate mechanisms for control of adaptive Th2 immunity.

Resident lung antigen-presenting cells have the capacity to promote Th2 T cell differentiation in situ.

Antigen exposure via airway epithelia is often associated with a failure to prime or with the preferential priming of Th2 cells. We previously reported that the intranasal delivery of a Th1-inducing antigen promoted Th2-dominated responses, rather than the expected Th1 responses. Thus, we proposed that when pulmonary T cell priming is induced, the lung microenvironment might intrinsically favor the generation of Th2 types of responses. To establish a potential mechanism for such preferential priming, we examined the initial interactions between antigens and resident antigen-presenting cells (APCs) within the lung. We show that intranasally delivered antigens are preferentially taken up and can be presented to antigen-specific T cells by a resident population of CD11c(bright) APCs. Most of these antigen-loaded APCs remained within lung tissues, and migration into secondary lymphoid organs was not crucial for T cell priming to occur within the pulmonary tract. Furthermore, these pulmonary APCs demonstrated a marked expression of IL-6 and IL-10 within hours of antigen uptake, suggesting that resident tissue APCs have the capacity to promote Th2 T cell differentiation in situ.

Generation of antigen-specific CD4+ T cell lines from naive precursors.

The conditions required for sensitizing naive T cells to nominal antigen are poorly understood. In this report we describe an in vitro system for generating antigen-specific CD4+ T cells from previously unprimed individuals. Freshly isolated CD4+ T cells were cultured with keyhole limpet hemocyanin (KLH), sperm whale myoglobin (SWM), or human immunodeficiency virus (HIV) gp160, antigens to which most persons have not been sensitized, in the presence of either dendritic cells (DC) or macrophages (M phi). In short-term (< 8 days) cultures, CD4+ T cells or their CD4+, CD45RA (naive) subpopulation mounted significant proliferative responses to KLH, SWM, and HIV gp160, but only if the antigens were presented by DC. In contrast, CD4+, CD45RO (memory) T cells responded poorly to these antigens, although they responded vigorously to tetanus toxoid, a recall antigen, presented by either DC or M phi. KLH- and SWM-specific CD4+ T cell lines were established from the starting population that had been sensitized in vitro, following repeated stimulation with antigen and M phi in medium supplemented with interleukin-2 and interleukin-4. Despite the continued presence of these cytokines during T cell expansion, the expanded lines retained their ability to respond to the priming antigen in the absence of exogenous cytokines. When the CD45RA and CD45RO subpopulations were sensitized and expanded separately, the CD45RA cells alone gave rise to antigen-specific T cell lines, while the CD45RO cells proliferated nonspecifically. These results demonstrate that human naive CD4+ T cells can be sensitized in vitro to nominal antigens presented by DC and that the sensitized cells can be expanded into long-term lines that retain their antigen specificity.

Generation of antigen-specific CD8+ CTLs from naive precursors.

Class I MHC-restricted CTLs are an important component of the host immune response against viral infections, and CTL effectors can often be isolated from infected individuals. However, the mechanism responsible for the induction of CTLs is incompletely understood because, in part, of the difficulty in generating such cells in vitro from naive precursors. In the present study we have used human peripheral blood dendritic cells (DCs), devoid of CD4+ T cells, to sensitize naive CD8+ T cells to exogenous Ags, resulting in the generation of Ag specific CTL effectors. With this system, Ag-specific CTL lines were generated to a complex glycoprotein, keyhole limpet hemocyanin, and to multiple small (9-15 amino acids) synthetic peptides derived from conserved regions of the HIV-1 gag and envelope proteins. The HIV-1-specific CTLs demonstrated potent HLA class I restricted killing of both Ag pulsed and virally infected target cells. In contrast to Ag-pulsed DCs, Ag-pulsed monocytes failed to sensitize CTL precursors although they could be used as feeders for purposes of CTL expansion and as target cells in cytolytic assays. With the use of the system described herein, a detailed analysis of the primary human T cell response to foreign Ags is now feasible, and CTL of desired specificity can be generated for potential clinical use in adoptive immunotherapy protocols.