Varicella-zoster virus-specific cell-mediated immune responses in HIV-infected adults.

The incidence of herpes zoster remains high in HIV-infected patients despite the use of combined antiretroviral therapy (cART). We wished to assess varicella-zoster virus (VZV)-specific cell-mediated immune (CMI) responses in HIV-infected adults on cART. VZV-specific CMI responses were assessed using lymphocyte proliferative responses, cytokine production (IL-2, TNF-α, and IFN-γ), and interferon-γ ELISPOT assays in 103 HIV-infected adults and 30 healthy controls. HIV-infected patients were analyzed according to their current and nadir CD4 cell count and their use of cART. A multivariate analysis was performed to identify factors associated with VZV-specific CMI responses. HIV-infected patients had lower VZV-specific CMI responses than healthy controls. Patients with a CD4 T cell count <100/µL had almost no detectable responses whereas those with a current CD4 T cell count >300/µL and suppressed viral replication on cART had responses similar to those of healthy controls. In multivariate analysis, factors significantly associated with VZV-specific CMI responses were the absence of a previous AIDS-defining event and higher CD4 cell counts, in particular central and effector memory CD4 T cell counts. HIV-infected patients with a history of AIDS or low CD4 cell counts have impaired VZV-specific CMI responses, and remain at risk for herpes zoster.

Autoimmunity in common variable immunodeficiency: correlation with lymphocyte phenotype in the French DEFI study.

Common variable immunodeficiency (CVID) is the most frequent clinically expressed primary immunodeficiency in adults and is characterized by primary defective immunoglobulin production. Besides recurrent infectious manifestations, up to 20% of CVID patients develop autoimmune complications. In this study, we took advantages of the French DEFI database to investigate possible correlations between peripheral lymphocyte subpopulations and autoimmune clinical expression in CVID adult patients. In order to analyse homogeneous populations of patients with precise clinical phenotypes, we first focused on patients with autoimmune cytopenia because they represent prototypic autoantibody mediated diseases. In a secondary analysis, we have tested our conclusions including all "autoimmune" CVID patients. We describe one of the largest European studies with 311 CVID patients, including 55 patients with autoimmune cytopenia and 61 patients with clinical or serologic autoimmune expression, excluding autoimmune cytopenia. We clarify previous reports and we confirm a very significant correlation between an increased proportion of CD21(low) B cells and CVID associated autoimmune cytopenia, but independently of the presence of other autoimmune disorders or of splenomegaly. Moreover, in CVID associated autoimmune cytopenia, T cells display an activated phenotype with an increase of HLA-DR and CD95 expression and a decrease in the naïve T cell numbers. Patients with other autoimmune manifestations do not harbour this "T and B cells phenotypic picture". In view of recent findings on CD21(low) B cells in CVID and RA, we suggest that both a restricted subset of B cells and a T cell help are required for a breakdown of B cell tolerance against membrane auto antigens in CVID.

Remission of severe CD8(+) cytotoxic T cell skin infiltrative disease in human immunodeficiency virus-infected patients receiving highly active antiretroviral therapy.

BACKGROUND: A CD8 cutaneous lymphoinfiltrative disease has been described in human immunodeficiency virus (HIV)-infected patients presenting with a severe erythroderma. The true nature of this severe skin infiltrative disorder is still elusive. Although some clinical features of this syndrome have raised the hypothesis of its malignant nature in initial observations, several studies have provided stronger support to the hypothesis that it is a reactive pseudotumoral process. METHODS: From 1995 through 2008, 8 HIV type 1 (HIV-1)-infected patients presenting with a chronic skin eruption, diagnosed as CD8 T cell infiltration of the skin, were studied. RESULTS: All patients showed diffuse infiltrated skin with superficial lymphadenopathy. A profound CD4(+) lymphocytopenia and eosinophilia were other major features. Histological and immunostaining analysis revealed a predominant dermal and epidermal infiltration by CD8(+) T cells belonging to the cytotoxic lineage, without evidence for a monoclonal status by polymerase chain reaction-based molecular analysis of lesional skin. A remission of skin symptoms occurred in all cases following highly active antiretroviral therapy, which paralleled the decrease of HIV-1 RNA load and the increase of CD4(+) peripheral blood absolute count. CONCLUSIONS: Altogether, these results emphasize the reactive, nonmalignant nature of this syndrome and strongly support the coupling between HIV-induced immune deficiency and uncontrolled CD8 activation.

B-cell and T-cell phenotypes in CVID patients correlate with the clinical phenotype of the disease.

BACKGROUND: Common variable immunodeficiency (CVID) is a heterogeneous disorder characterized by recurrent infections and defective immunoglobulin production. METHODS: The DEFI French national prospective study investigated peripheral T-cell and B-cell compartments in 313 CVID patients grouped according to their clinical phenotype, using flow cytometry. RESULTS: In patients developing infection only (IO), the main B-cell or T-cell abnormalities were a defect in switched memory B cells and a decrease in naive CD4(+) T cells associated with an increase in CD4(+)CD95(+) cells. These abnormalities were more pronounced in patients developing lymphoproliferation (LP), autoimmune cytopenia (AC), or chronic enteropathy (CE). Moreover, LP and AC patients presented an increase in CD21(low) B cells and CD4(+)HLA-DR(+) T cells and a decrease in regulatory T cells. CONCLUSION: In these large series of CVID patients, the major abnormalities of the B-cell and T-cell compartments, although a hallmark of CVID, were only observed in half of the IO patients and were more frequent and severe in patients with additional lymphoproliferative, autoimmune, and digestive complications.

Cellular CD4 T cell responses to the diphtheria-derived carrier protein of conjugated pneumococcal vaccine and antibody response to pneumococcal vaccination in HIV-infected adults.

BACKGROUND: The French National Agency for AIDS and Viral Hepatitis Research (ANRS) 114 Pneumovac trial showed that a strategy combining a 7-valent pneumococcal conjugate vaccine (PCV) prime at week 0 followed by a 23-valent pneumococcal polysaccharide vaccine (PPV) boost at week 4 enhances the frequency and magnitude of immunoglobulin (Ig) G responses against Streptococcus pneumoniae polysaccharides (SPPs) compared with PPV alone. CD4 T cell responses specific to the diphtheria-derived carrier protein CRM(197) were evaluated. METHODS: Lymphocyte proliferative responses (LPRs) and T(H)1 cytokine T cell responses against the diphtheria-derived carrier protein CRM(197) contained in the PCV were investigated at weeks 0, 4, and 24. RESULTS: In the prime-boost PCV and PPV group, the magnitude of LPRs to diphtheria toxoid and CRM(197) increased at week 4 (P < .001) and persisted until week 24 (P = .08 and .13, respectively, compared with week 4). Interferon-gamma and interleukin-2 production to CRM(197) increased significantly at week 4 (P = .02 and P < .001, respectively) and remained stable until week 24 (P = .28 and P = .08, respectively). No changes were detected in the PPV group. A strong association among the magnitude of LPRs to CRM(197) at week 4, the breadth of SPP specific IgG responses at week 8 (P = .03), and sustained IgG responses at week 24 was observed. A high frequency of helper follicular CD4(+)CXCR5(+) T cells at baseline was associated with a better LPR response to CRM(197.) CONCLUSIONS: The PCV prime-elicited memory T cell responses were associated with better and sustained humoral SPP specific IgG responses. ClinicalTrials.gov identifier. NCT00148824.

Long-term immune deficiency after allogeneic stem cell transplantation: B-cell deficiency is associated with late infections.

Immune reconstitution was analyzed in 140 consecutive patients who were 2-year disease-free and who underwent myeloablative allogeneic transplantation. A CD4 and CD8 defect was observed involving naive, terminally differentiated, memory and competent cells and above limits values for activated subsets. Natural killer cells normalize at six months while we observed expansion of CD19(+)/CD5(+) B cells after three months and a persisting defect of memory B cells. Chronic graft-versus-host disease did not influence significantly those parameters for CD8 subsets while the naïve and competent CD4 subsets were strongly affected. But the most profound impact of chronic graft-versus-host disease was on B-cell subsets, especially on the memory B population. The cumulative incidence of late severe infections was low (14% at four years). Using Cox's models, only low B-cell counts at 12 (P=0.02) and 24 (P=0.001) months were associated with the hazard of developing late infection, in particular if patients did not develop chronic graft-versus-host disease.

Late-onset combined immune deficiency: a subset of common variable immunodeficiency with severe T cell defect.

BACKGROUND: Common variable immunodeficiency (CVID) is a primary immune deficiency defined by defective antibody production. In most series, a small proportion of patients present with opportunistic infections (OIs). METHODS: The French DEFI study has enrolled patients with primary hypogammaglobulinemia and allows a detailed clinical and immunologic description of patients with previous OIs and/or at risk for OIs. RESULTS: Among 313 patients with CVID, 28 patients (8.9%) presented with late-onset combined immune deficiency (LOCID), defined by the occurrence of an OI and/or a CD4(+) T cell count <200 x 10(6) cells/L, and were compared with the remaining 285 patients with CVID. The patients with LOCID more frequently belonged to consanguineous families (29% vs 8%; P = .004). They differed from patients with CVID with a higher prevalence of splenomegaly (64% vs 31%), granuloma (43% vs 10%), gastrointestinal disease (75% vs 42%), and lymphoma (29% vs 4%). Even on immunoglobulin substitution, they required more frequent antibiotics administration and hospitalization. Lymphocyte counts were lower, with a marked decrease in CD4(+) T cell counts (158 x 10(6) vs 604 x 10(6) cells/L; P < .001) and a severe defect in naive CD45RA(+)CCR7(+)CD4(+) T cell counts (<20% of total CD4(+) T cells in 71% of patients with LOCID vs 37% of patients with CVID; P = .001). The CD19(+) B cell compartment was also significantly decreased (20 x 10(6) vs 102 x 10(6) cells/L; P < .001). CONCLUSIONS: LOCID differs from classic CVID in its clinical and immunologic characteristics. Systematic T cell phenotype may help to discriminate such patients from those with CVID. Identification of this phenotype should result in a more fitted diagnostic and therapeutic approach of infections and could provide insights for genetic diagnosis.

Acute graft-versus-host disease transiently impairs thymic output in young patients after allogeneic hematopoietic stem cell transplantation.

Long-term T-cell reconstitution after hematopoietic stem cell transplantation (HSCT) is dependent on patient thymic function and affected by graft-versus-host disease (GVHD). To assess the impact of acute GVHD (aGVHD) on thymic function, we followed a cohort of 93 patients who received HSCT from a human histocompatibility leukocyte antigen-identical sibling, mainly for hematologic malignancies. Thymic output was measured by signal-joint T-cell receptor excision circles (sjTREC) real-time polymerase chain reaction. Absolute sjTREC number was lower at 6 months in patients with aGVHD (P = .014), associated with lower absolute counts of naive CD4 T cells at 6 and 12 months (P = .04 and .02), and persistent abnormalities in T-cell repertoire diversity. Age and aGVHD affected thymic function independently in multivariate analysis. In patients less than 25 years of age, thymic function recovered almost totally at 1 year. As a marker of thymocyte proliferation, we quantified the betaTREC generated during the T-cell receptor beta-chain recombination, in a group of 20 age-matched patients. Mean betaTREC level was reduced at 6 months in patients with aGVHD, indicating an impact on early thymic differentiation rather than on intrathymic proliferation. These data show that aGVHD or its treatment has a transient impact on thymic function in younger patients in the first months after HSCT.

Restoration of Toxoplasma gondii-specific immune responses in patients with AIDS starting HAART.

OBJECTIVE: To study the kinetics and identify factors associated with Toxoplasma-specific immune responses in patients with AIDS starting antiretroviral therapy. METHODS: A prospective study of 38 HIV-infected patients seropositive for Toxoplasma who started antiretroviral therapy with CD4 T cells less than 200 cells/microl. T-cell and B-cell phenotypes, anti-Toxoplasma antibodies titers, Th-1 and Th-2 cytokine production and lymphocyte proliferative responses (LPRs) to Toxoplasma were assessed over 12 months. RESULTS: Median CD4 cell count increased from 122 cells/microl at baseline to 260 cells/microl at 12 months, and the incidence of a positive LPR from 18.4 to 70.5%. A Toxoplasma IgG titer more than 150 IU/ml was the only baseline variable associated with a positive LPR (hazard ratio: 4.6, P = 0.003). Among time-dependent covariates, the number of effector memory (CD45RA-CCR7-) CD4 T cells was associated with a positive LPR (P < 0.02) and the number of terminally differentiated (CD45RA+CCR7-) CD8 T cells was associated with in-vitro production of gamma-IFN (P < 0.008). CONCLUSION: Among patients with low CD4 cell counts, high anti-Toxoplasma IgG titers were associated with LPR to Toxoplasma antigen. After starting antiretroviral therapy, the number of effector memory CD4 T cells and terminally differentiated CD8 T cells were associated with the restoration of Toxoplasma LPR and gamma-IFN production, respectively.

An unusual CD56(bright) CD16(low) NK cell subset dominates the early posttransplant period following HLA-matched hematopoietic stem cell transplantation.

The expansion of the cytokine-producing CD56(bright) NK cell subset is a main feature of lymphocyte reconstitution after allogeneic hematopoietic stem cell transplantation (HSCT). We investigated phenotypes and functions of CD56(bright) and CD56(dim) NK subsets from 43 HLA-matched non-T cell-depleted HSCT donor-recipient pairs. The early expansion of CD56(bright) NK cells gradually declined in the posttransplant period but still persisted for at least 1 year and was characterized by the emergence of an unusual CD56(bright)CD16(low) subset with an intermediate maturation profile. The activating receptors NKG2D and NKp46, but also the inhibitory receptor NKG2A, were overexpressed compared with donor CD56(bright) populations. Recipient CD56(bright) NK cells produced higher amounts of IFN-gamma than did their respective donors and were competent for degranulation. Intracellular perforin content was increased in CD56(bright) NK cells as well as in T cells compared with donors. IL-15, the levels of which were increased in the posttransplant period, is a major candidate to mediate these changes. IL-15 serum levels and intracellular T cell perforin were significantly higher in recipients with acute graft-vs-host disease. Altogether, CD56(bright) NK cells postallogeneic HSCT exhibit peculiar phenotypic and functional properties. Functional interactions between this subset and T cells may be important in shaping the immune response after HSCT.

Infections in 252 patients with common variable immunodeficiency.

BACKGROUND: Common variable immunodeficiency is characterized by recurrent infections and defective immunoglobulin production. METHODS: The DEFI French national study prospectively enrolled adult patients with primary hypogammaglobulinemia. Clinical events before inclusion were retrospectively analyzed at that time. RESULTS: From April 2004 through April 2007, 341 patients were enrolled, 252 of whom had received a diagnosis of common variable immunodeficiency; of those, 110 were male, 142 were female, and 228 were white. The median age at first symptoms was 19 years. The median age at common variable immunodeficiency diagnosis was 33.9 years. The median delay for diagnosis was 15.6 years for the 138 patients with initial symptoms before 1990 and 2.9 years for the 114 patients with initial symptoms from 1990 to the time of the study. The most frequent initial symptoms were upper respiratory tract infections: bronchitis (in 38% of patients), sinusitis (36%), pneumonia (31%), and/or bronchiectasis (14%). Overall, 240 patients had respiratory symptoms. Pneumonia was reported in 147 patients; Streptococcus pneumoniae and Haemophilus influenzae were documented in 46 and 17 cases, respectively. Recurrent or chronic diarrhea was reported in 118 patients. Giardia (35 cases), Salmonella (19), and Campylobacter (19) infections were more frequent in patients with undetectable serum immunoglobulin A (P<.001). Sixteen patients developed opportunistic infections. Persistent infections and requirement for antibiotics despite immunoglobulin substitution correlated with severe defect of memory switched B cells (P=.003) but not with immunoglobulin G trough levels (P=.55). CONCLUSION: Although reduced within the past decade, the delay of diagnosis of common variable immunodeficiency remains unacceptable. Recurrence of upper respiratory tract infection or pneumonia should lead to systematic evaluation of serum immunoglobulin.

Primary Epstein-Barr virus infection with pneumonia transmitted by allogeneic bone marrow after transplantation.

We report a case of primary Epstein-Barr virus infection with lung involvement occurring 1 month after bone marrow transplantation. The transplant recipient had serological test results that were negative for Epstein-Barr virus before transplantation. The virus must have been transmitted by the donor's bone marrow, which was positive for Epstein-Barr virus. The patient recovered after rituximab and corticosteroid therapy.

Kaposi's sarcoma-associated herpesvirus viremia is associated with the progression of classic and endemic Kaposi's sarcoma.

In order to gain further insight on the role of Kaposi's sarcoma-associated herpesvirus (KSHV) in classic and endemic Kaposi's sarcoma (KS) pathogenesis, we aimed to determine (i) whether KSHV is detectable in peripheral blood mononuclear cells (PBMCs), (ii) which PBMCs subpopulation harbor the virus, (iii) which clinical, histologic, and immunologic parameters are associated with KSHV viremia in a population of classic and endemic KS. KSHV viremia and various immunologic parameters were screened on 81 patients. KSHV viremia was positive in 58% of the patients. KSHV was detected in B cells, T cells, and monocytes. CD34+ cells depleted in circulating endothelial cells (CECs) were never infected and 50% of the patients tested had CECs infected by KSHV. We observed a significant increase of IL-2 and IFN-gamma production by CD4 T cells and an increase of IFN-gamma production by CD8 T cells compared to control patients. KS progression (P = 0.001) and KS staging (P = 0.03) were significantly and independently associated with positive KSHV viremia. Our results show that there is no specific immunosuppression in classic or endemic KS. We showed that KSHV can be detected within CECs and that KSHV viremia could be an indicator of circulating mature or precursor spindle cells.

Failure of rituximab in human immunodeficiency virus-associated multicentric Castleman disease.

Two human immunodeficiency virus-infected patients who needed etoposide therapy to control exacerbations of Castleman disease received four infusions of rituximab. Clinical and virologic relapses with increased blood human herpesvirus-8 DNA levels occurred in both patients 4 and 24 weeks later and were associated with a worsening of Kaposi sarcoma.

[Treatment interruption in 30 HIV-infected patients with successful viral suppression under highly active antiretroviral treatment]. / Interruptions du traitement antirétroviral chez 30 patients infectés par le VIH en succès virologique.

OBJECTIVE: To evaluate clinical and laboratory results in HIV-infected patients with complete viral suppression under HAART (highly active antiretroviral treatment) for whom treatment was interrupted and to identify risk factors associated with prolonged (i.e., successful) treatment interruption. METHODS: Retrospective study of patients who interrupted therapy while on HAART with a plasma HIV RNA <400 copies/mL. Multivariate regression analysis was performed to identify factors associated with a prolonged interruption (more than 6 months). RESULTS: 36 treatment interruptions in 30 patients were analyzed. Patients' mean age was 42 years, 83% were men, and 60% were infected through homosexual contact. Median CD4 cell count at initiation of HAART was 292/mm3 and median viral load 43,000 copies/mL. Reported reasons for HAART discontinuation included patient or clinician choice (n=21) or drug toxicity (n=15). Median CD4 cell count when treatment interruption began was 606/mm3, and its median duration was 14 months. During treatment interruption, adverse clinical events or laboratory findings occurred in 9 patients (30%), all of whom had a CD4 cell count nadir < 300/mm3. When HAART resumed, median CD4 cell count was 302/mm3, and median viral load 59,800 copies/mL. Plasma HIV RNA dropped to <400 copies/mL in all patients within 4 months of resuming treatment. In multivariate analysis, the factors associated with resuming HAART within 6 month of treatment interruption were: HAART including non-nucleoside analog (adjusted Hazard Ratio [aHR]: 3.6, 95% CI: 1.2-10.6, p = 0.02), a CD4 cell count nadir < 300 (adjusted Hazard Ratio [aHR]: 5.5, 95% CI: 2.0-26, p = 0.0057), undetectable plasma HIV RNA for longer than 21 months at the interruption (aHR: 7.2, 95% CI: 2-26, p = 0.002). This probability was 45.5% in patients with a CD4 cell count nadir < 300 and 14.3% in the others (p 0.10). CONCLUSION: Antiretroviral treatment should be interrupted only with caution in patients with a CD4 cell count nadir <300/mm3 because of the risk of adverse clinical events or laboratory findings.

Therapeutic immunization with a human immunodeficiency virus (HIV) type 1-recombinant canarypox vaccine in chronically HIV-infected patients: The Vacciter Study (ANRS 094).

This open single-arm study evaluated whether the administration of an HIV-recombinant canarypox vaccine (vCP1433) in highly active antiretroviral therapy (HAART)-treated patients chronically infected with HIV was safe, immunogenic and associated with prolongation of treatment discontinuation: 48 patients received four monthly vCP1433 injections and stopped HAART. Immunization was safe. HIV-p24-specific lymphoproliferative responses (LPR), significantly increased in the whole group after two injections but decreased thereafter, HIV-gag-specific CD8 T cells were boosted in 55% patients tested. Altogether, 11% patients with at least one HIV-specific LPR during immunization remained off therapy after 44 weeks of interruption. Detection of such LPR response at the time of treatment interruption was significantly associated with the probability of remaining off therapy. These results provide rationale for future randomized trials exploring this strategy.

Analysis of immune reconstitution after autologous bone marrow transplantation in systemic sclerosis.

OBJECTIVE: To analyze hematopoietic and immune reconstitution after autologous hematopoietic stem cell transplantation (HSCT) in 7 patients with systemic sclerosis (SSc). METHODS: Two groups of patients were retrospectively constituted according to whether they had a favorable clinical response (group A; n = 4) or no response or a relapse of disease (group B; n = 3) after HSCT. Immune reconstitution was analyzed every 3 months using lymphocyte immunophenotyping, alpha/beta T cell receptor (TCR) diversity analysis, and ex vivo thymic function analysis by quantification of TCR rearrangement excision circles (TRECs). RESULTS: Patients had similar characteristics at study entry, except for a lower modified Rodnan skin thickness score (P = 0.03) and a lower Health Assessment Questionnaire score (P = 0.05) in group A than in group B. The number of reinjected cells and the time to hematopoietic reconstitution were similar in both groups. The absolute numbers of CD19+ and CD20+ B cells were lower in group A than in normal controls (P < 0.05) and within the normal range in group B. Absolute numbers of T and natural killer lymphocytes were normal before HSCT. Numbers of CD3+ cells remained low thereafter. Numbers of CD8+ cells were back to normal 3 months after HSCT in both groups. B cell counts were low until 6 months after HSCT in group A and stayed in the normal range in group B. The CD3+ defect was sustained in group A, with an opposite trend and a faster CD4+ reconstitution profile in group B. The T cell repertoire was skewed before and until 1 year after HSCT, with shared expansions before and after transplant in a given individual. TREC values correlated negatively with C-reactive protein levels (r(s) = -0.41, P = 0.001) and positively with CD19+ (r(s) = 0.35, P = 0.001) and CD20+ (r(s) = 0.34, P = 0.002) lymphocyte counts. CONCLUSION: B and T lymphocyte populations remained disturbed for at least 1 year after HSCT in SSc patients, which may reflect the persistence of an underlying disease mechanism.

Prognostic value of pretransplantation host thymic function in HLA-identical sibling hematopoietic stem cell transplantation.

Thymic function is critical for immune reconstitution after hematopoietic stem cell transplantation (HSCT). We evaluated recipient thymic function before HSCT by quantifying T-cell receptor excision circles (TRECs) in pretransplantation peripheral blood lymphocytes from 102 patients who received HSCs from an HLA-identical sibling for malignant (n = 87) or nonmalignant diseases (n = 15). Median TREC value before transplantation was 257 TRECs per 150,000 CD3+ cells (range, 0-42,746). We assessed 172 TRECs per 150,000 CD3+ cells as the most discriminating TREC value for survival in a first cohort of patients (n = 62). This cut-off was validated in a second independent prospective group of 40 patients. In the 102 patients, a TREC value greater than or equal to 172 was associated with a better survival (P < .000 01), a decreased incidence of grade II-IV acute graft-versus-host disease (GVHD; P = .017), chronic GVHD (P = .023), and bacterial (P = .003) and cytomegalovirus (CMV) infection (P = .024). In a multivariate analysis, low pretransplantation TREC values were associated with a higher incidence of CMV infection (hazard ratio [HR] = 2.0, P = .06) and severe bacterial infections (HR = 2.8, P = .036). Finally, high TREC values (HR = 6.6, P = .002) and ABO compatibility (HR = 2.7, P = .02) were associated with a better survival. Therefore, recipient host thymic function assessment could be helpful in predicting HSCT outcome and identifying patients who require a close immunologic monitoring.

Epstein-Barr virus (EBV) reactivation in allogeneic stem-cell transplantation: relationship between viral load, EBV-specific T-cell reconstitution and rituximab therapy.

BACKGROUND: Monitoring of Epstein-Barr virus (EBV) reactivation after allogeneic hematopoietic stem-cell transplantation markedly improved with quantitative real-time polymerase chain reaction amplification of EBV DNA and visualization of EBV-specific CD8+ T cells with peptide-human leukocyte antigen (HLA) class I tetramers. We decided to combine these methods to evaluate posttransplant EBV reactivation and rituximab therapy. METHODS: We followed 56 patients treated with an HLA-genoidentical sibling (n=32), an HLA-matched unrelated donor (MUD, n=19), or an unrelated cord-blood transplant (n=5). EBV DNA was quantified in plasma and in peripheral blood mononuclear cells (PBMC). Patient CD8+ T cells were stained with a panel of eight tetramers. RESULTS: EBV DNA was detected in half of the patients, mainly in the MUD group (17/19). In 19 patients, viral DNA was detected only in the cellular compartment. All patients who controlled reactivation without rituximab and despite a viral load of greater than 500 genome equivalents (gEq)/150,000 PBMC mounted an EBV-specific CD8+ T-cell response in greater than 1.4% of CD3+CD8+ T cells. Plasmatic EBV genome was found in nine patients preceded by a high cellular viral load. Three of these patients controlled the reactivation before or without the introduction of rituximab, and they all developed a significant and increasing EBV-specific T-cell response. Patients with EBV-specific T cells at the onset of reactivation controlled viral reactivation without rituximab. CONCLUSION: This study emphasizes the benefit of an early and close monitoring of EBV reactivation and CD8+-specific immune responses to initiate rituximab only when necessary and before the immune response becomes overwhelmed by the viral burden.

IL-2 therapy and thymic production of naive CD4 T cells in HIV-infected patients with severe CD4 lymphopenia.

OBJECTIVES: IL-2 therapy increases memory and naive CD4 T cells in HIV-infected patients, but its effect on thymopoiesis is unknown. To investigate this effect, we quantified T-cell receptor rearrangement excision circles (TREC) in CD4 T cells from lymphopenic AIDS patients treated with highly active antiretroviral therapy and IL-2. METHODS: CD4 cell subsets were evaluated by flow cytometry using anti-CD45RO/RA, CD62L, Ki67 and CD95 monoclonal antibodies. The proportion of recent thymic emigrant had been quantified by a real-time polymerase chain reaction assay for signal joint TREC in peripheral blood mononuclear and purified CD4 T cells. RESULTS: At initiation of IL-2, TREC copies/microl of blood were correlated with naive T cell numbers and age. Both naive and TREC numbers/microl significantly increased over time in all patients, with a wide range of TREC increases. Higher percentages of CD4+CD45RO-negative cells positive for the Ki67 cell-cycle marker were found in patients with a low TREC increase, but remained stable under IL-2. TREC and naive cell recovery were correlated; they also correlated with the numbers of TREC and naive cells at the start of IL-2, and with age, suggesting a thymic origin for naive T-cell recovery. A mathematical model showing the linear recovery of naive cells and TREC under IL-2 also strongly suggested that a naive T-cell increase reflects thymic export and involves little net death and proliferation. CONCLUSION: Although we cannot rule out a mechanism of altered proliferation or death rate, the thymus plays an important role in the long-term recovery of naive T cells under IL-2 therapy.