Expression of CD69 after in vitro stimulation: a rapid method for quantitating impaired lymphocyte responses in HIV-infected individuals

Monitoring the responsiveness of T and antigen presenting cell compartments in breast cancer patients is useful to predict clinical tumor response to neoadjuvant chemotherapy

Background

Vaccination of mice with tumors treated with Doxorubicin promotes a T cell immunity that relies on dendritic cell (DC) activation and is responsible for tumor control in vaccinated animals. Despite Doxorubicin in combination with Cyclophosphamide (A/C) is widely used to treat breast cancer patients, the stimulating effect of A/C on T and APC compartments and its correlation with patient’s clinical response remains to be proved.

Methods

In this prospective study, we designed an in vitro system to monitor various immunological readouts in PBMCs obtained from a total of 17 breast cancer patients before, and after neoadjuvant anti-tumor therapy with A/C.

Results

The results show that before treatment, T cells and DCs, exhibit a marked unresponsiveness to in vitro stimulus: whereas T cells exhibit poor TCR internalization and limited expression of CD154 in response to anti-CD3/CD28/CD2 stimulation, DCs secrete low levels of IL-12p70 and limited CD83 expression in response to pro-inflammatory cytokines. Notably, after treatment the responsiveness of T and APC compartments was recovered, and furthermore, this recovery correlated with patients’ residual cancer burden stage.

Conclusions

Our results let us to argue that the model used here to monitor the T and APC compartments is suitable to survey the recovery of immune surveillance and to predict tumor response during A/C chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3982-1) contains supplementary material, which is available to authorized users.

Evaluation of T and B lymphocyte function in clinical practice using a flow cytometry based proliferation assay

The golden standard for functional evaluation of immunodeficiencies is the incorporation of [(3)H]-thymidine in a proliferation assay stimulated with mitogens. Recently developed whole blood proliferation assays have the advantage of parallel lymphocyte lineage analysis and in addition provide a non-radioactive alternative. Here we evaluate the Flow-cytometric Assay for Specific Cell-mediated Immune-response in Activated whole blood (FASCIA) in a comparison with [(3)H]-thymidine incorporation in four patients with severe combined immunodeficiency. The threshold for the minimum number of lymphocytes required for reliable responses in FASCIA is determined together with reference values from 100 healthy donors when stimulated with mitogens as well as antigen specific stimuli. Finally, responses against PWM and SEA+SEB stimuli are conducted with clinically relevant immunomodulatory compounds. We conclude that FASCIA is a rapid, stable and sensitive functional whole blood assay that requires small amounts of whole blood that can be used for reliable assessment of lymphocyte reactivity in patients.

The early activation of CD8+ T cells is dependent on type I IFN signaling following intramuscular vaccination of adenovirus vector

Few of the vaccines in current use can induce antigen- (Ag-) specific immunity in both mucosal and systemic compartments. Hence, the development of vaccines that realize both mucosal and systemic protection against various pathogens is a high priority in global health. Recently, it has been reported that intramuscular (i.m.) vaccination of an adenovirus vector (Adv) can induce Ag-specific cytotoxic T lymphocytes (CTLs) in both systemic and gut mucosal compartments. We previously revealed that type I IFN signaling is required for the induction of gut mucosal CTLs, not systemic CTLs. However, the molecular mechanism via type I IFN signaling is largely unknown. Here, we report that type I IFN signaling following i.m. Adv vaccination is required for the expression of type I IFN in the inguinal lymph nodes (iLNs), which are the draining lymph nodes of the administration site. We also showed that the type I IFN signaling is indispensable for the early activation of CTLs in iLNs. These data suggested that type I IFN signaling has an important role in the translation of systemic innate immune response into mucosal adaptive immunity by amplifying the innate immune signaling and activating CTLs in the iLN.

Comparison of HDAC inhibitors in clinical development: effect on HIV production in latently infected cells and T-cell activation

Objective: We aimed to compare the potential for inducing HIV production and the effect on T-cell activation of potent HDAC inhibitors undergoing clinical investigation.

Design: In vitro study

Methods: The latently infected cell lines ACH2 and U1 were treated with the HDAC inhibitors panobinostat, givinostat, belinostat, vorinostat and valproic acid. Viral induction was estimated by p24 production. Peripheral blood mononuclear cells from uninfected donors were treated with the HDAC inhibitors and the expression of activation markers on T-cell phenotypes was measured using flow cytometry. Finally, the ability of givinostat, belinostat and panobinostat to reactivate latent HIV-1 expression in primary T-cells was investigated employing a CCL19-induced latent primary CD4+ T cell infection model.

Results: The various HDAC inhibitors displayed significant potency differences in stimulating HIV-1 expression from the latently infected cell lines with panobinostat > givinostat ≈belinostat > vorinostat > valproic acid. Panobinostat was significantly more potent than all other HDAC inhibitors and induced virus production even in the very low concentration range 8–31 nM. The proportion of primary T-cells expressing the early activation marker CD69 increased moderately in all HDAC inhibitor-treated cells compared with untreated cells. Finally, proof was obtained that panobinostat, givinostat and belinostat induce virus production in latently infected primary cells at therapeutic concentrations with panobinostat being the most potent stimulator.

Conclusion: At therapeutic concentrations panobinostat stimulate HIV-1 expression in latently infected cells with greater potency than other HDAC inhibitors undergoing clinical investigation. These findings warrant further investigation and panobinostat is now being advanced into clinical testing against latent HIV infection.

Biomarkers of immune dysfunction following combination antiretroviral therapy for HIV infection

Combination antiretroviral therapy (cART) has significantly reduced morbidity and mortality of HIV-infected patients, yet their life expectancy remains reduced compared with the general population. Most HIV-infected patients receiving cART have some persistent immune dysfunction characterized by chronic immune activation and premature aging of the immune system. Here we review biomarkers of T-cell activation (CD69, -25 and -38, HLA-DR, and soluble CD26 and -30); generalized immune activation (C-reactive protein, IL-6 and D-dimer); microbial translocation (lipopolysaccharide, 16S rDNA, lipopolysaccharide-binding protein and soluble CD14); and immune dysfunction of specific cellular subsets (T cells, natural killer cells and monocytes) in HIV-infected patients on cART and their relationship to adverse clinical outcomes including impaired CD4 T-cell recovery, as well as non-AIDS clinical events, such as cardiovascular disease.

Evaluation of the expression of early activation marker CD69 by CD8+ lymphocytes in HIV-infected patients

We studied the expression of CD69 antigen on CD8+ lymphocytes in response to nonspecific activator phytohemagglutinin in 202 patients with HIV infection. It was found that the number of CD8+CD69+ lymphocytes in HIV-infected patients increased; this parameter negatively correlated with relative and absolute content of CD4+ cells and positively correlated with IgG concentration.

Aflatoxin-related immune dysfunction in health and in human immunodeficiency virus disease

Both aflatoxin and the human immunodeficiency virus (HIV) cause immune suppression and millions of HIV-infected people in developing countries are chronically exposed to aflatoxin in their diets. We investigated the possible interaction of aflatoxin and HIV on immune suppression by comparing immune parameters in 116 HIV positive and 80 aged-matched HIV negative Ghanaians with high (> or =0.91 pmol/mg albumin) and low (<0.91 pmol/mg albumin) aflatoxin B1 albumin adduct (AF-ALB) levels. AF-ALB levels and HIV viral load were measured in plasma and the percentages of leukocyte immunophenotypes and cytokine expression were determined using flow cytometry. The cross-sectional comparisons found that (1) among both HIV positive and negative participants, high AF-ALB was associated with lower perforin expression on CD8+ T-cells (P = .012); (2) HIV positive participants with high AF-ALB had significantly lower percentages of CD4+ T regulatory cells (Tregs; P = .009) and naive CD4+ T cells (P = .029) compared to HIV positive participants with low AF-ALB; and (3) HIV positive participants with high AF-ALB had a significantly reduced percentage of B-cells (P = .03) compared to those with low AF-ALB. High AF-ALB appeared to accentuate some HIV associated changes in T-cell phenotypes and in B-cells in HIV positive participants.

CD69 expression as an index of T-cell function: assay standardization, validation and use in monitoring immune recovery

BACKGROUND

CD69 is a surrogate marker of T-cell responsiveness to mitogen and Ag stimulus and can be used as a measure of T-lymphocyte activation. Quantitative flow cytometric determination of CD69 expression on T lymphocytes has several advantages over traditional lymphocyte proliferation assays, but this method has not yet been standardized for clinical applications.

METHODS

We qualified a commercially available assay using the manufacturer's procedures for measurement of T-cell response to a mitogen (PHA), superantigen (Staphylococcus endotoxin B; SEB) and Ca(2+) ionophore (phorbyl myristate acetate; PMA) with peripheral blood from healthy volunteers. Following this, we tested the usefulness of the assay in determining T-cell responses to PHA and SEB for six immunocompromised patients.

RESULTS

Healthy volunteers showed 17-fold increases in T-cell CD69 Ab bound per cell (ABC) with PHA stimulation compared with the baseline. SEB was also an effective T-cell activating agent, increasing CD69 ABC by 5-fold, comparable with results obtained with PMA stimulation. PHA- and SEB-stimulated T-cell CD69 ABC for patients 100 days post-BM transplant were generally below 1 SD of that from healthy volunteers. SEB-stimulated T-cell CD69 expression was significantly depressed for CD8(+) T cells while CD4(+) T-cell responses to SEB were generally within 1 SD of the mean for healthy volunteers.

DISCUSSION

These results suggest that quantitative measurement of CD69 surface expression by flow cytometry is a useful diagnostic tool for detailed assessment of T-lymphocyte and subset activation.

CD69 expression on CD4+ T lymphocytes after in vitro stimulation with tuberculin is an indicator of immune sensitization against Mycobacterium tuberculosis antigens

The expression of the CD69 antigen on CD4 T lymphocytes after in vitro stimulation with purified protein derivative (2 tuberculin units) was used to evaluate the tuberculin reactivities of 52 individuals from four experimental groups: Mycobacterium bovis BCG-vaccinated healthy individuals with a negative tuberculin skin test (TST) result (group A), BCG-vaccinated healthy individuals with a positive TST result (group B), patients with active tuberculosis (TB) before treatment (group C), and individuals with clinically inactive TB who had previously completed a prescribed course of chemotherapy (group D). The expression of CD69 on CD4 T lymphocytes was significantly higher in patients with active TB (16.2%+/-7.3%), individuals with clinically inactive TB (10.5%+/-7.4%), and healthy individuals with a positive TST result (15.5%+/-7.2%) than in healthy individuals with a negative TST result (3.8%+/-4.3%) (P<0.005). We confirmed the correlation between CD69 antigen expression on T lymphocytes after stimulation with tuberculin and the TST induration diameter (Spearman rho=0.783; P<0.001), an assay for gamma interferon (the Quantiferon-TB assay; Spearman rho=0.613; P<0.001), and the lymphocyte BLAST transformation test (Spearman rho=0.537; P<0.001). Our results demonstrate the usefulness of the determination of CD69 on CD4 T lymphocytes after in vitro stimulation with tuberculin as a rapid indicator of immune sensitization against Mycobacterium tuberculosis.

Effect of interleukin-15 on anti-CD3/anti-CD28 induced apoptosis of umbilical cord blood CD4+ T cells

OBJECTIVES

Interleukin-15 (IL-15) has potential therapeutic advantage for patients receiving umbilical cord blood (CB) transplantation. The present study aims to examine the ability of IL-15 to modulate the survival, maturation, and function of anti-CD3/anti-CD28 stimulated CB CD4+ T cells, in comparison with responses from adult peripheral blood (APB) CD4+ T cells.

METHODS

Enriched CB and APB CD4+ T cells were stimulated with anti-CD3 and anti-CD28 (anti-CD3/anti-CD28) in the presence or absence of IL-15 (10 ng/mL) for 5 d. The percentages of apoptotic cells were assessed by propidium iodide/annexin-V flow cytometric staining. T-cell activation was analyzed with the expression of surface markers (CD45RO/CD69/CD25). Interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) production in culture supernatant was determined by enzyme-linked immunosorbent assay.

RESULTS

CB CD4+ T cells had a higher survival and lower apoptotic response following anti-CD3/anti-CD28 stimulation, compared with APB CD4+ T cells. IL-15 enhanced apoptosis and promoted CD45RO conversion of anti-CD3/anti-CD28 activated CB CD4+ T cells, an effect not observed with APB CD4+ T cells. Although activated CB CD4+ T cells expressed comparable level of CD69/CD25 expression to adults, IFN-gamma production of activated CB CD4+ T cells was markedly deficient compared with that of corresponding APB CD4+ T cells. Exogenous IL-15 further enhanced the production of IFN-gamma, but not TNF-alpha, of activated CB CD4+ T cells.

CONCLUSIONS

IL-15 preferentially resulted in an activation-enhancing effect on CB CD4+ T cells, accompanied by increased apoptosis. Our finding may have therapeutic implications while designing IL-15 immunotherapy for patients receiving CB transplant.

Effect of interleukin 15 and interleukin 2 on anti-CD3-induced T-cell activation and apoptosis in children with common variable immunodeficiency

BACKGROUND

Defective T-cell function and susceptibility to apoptosis following activation may contribute to the immunodeficiency observed in common variable immunodeficiency (CVID) patients. Interleukin (IL) 2 benefits CVID children by boosting T-cell function.

OBJECTIVE

To investigate the effect of another IL-2 common gamma-chain signaling cytokine, IL-15, on T-cell activation and apoptosis of peripheral blood mononuclear cells (PBMCs) from children with CVID compared with IL-2.

METHODS

Five children treated at the Chang Gung Children's Hospital, Taoyuan, Taiwan, during 1998 to 2002 who fulfilled World Health Organization criteria for CVID and 8 age-matched, healthy controls were enrolled. The PBMCs were stimulated with anti-CD3 in the presence or absence of IL-2 and IL-15 for 4 days, followed by 24-hour incubation with anti-Fas to induce apoptosis. Surface expression of CD69, CD25, and CD95 (Fas) on CD3+ T cells was evaluated by flow cytometry. The degree of apoptosis was evaluated by propidium iodide-phycoerythrin/annexin V-fluorescein isothiocyanate flow cytometric staining.

RESULTS

Following anti-CD3 activation, CD69 and CD25 expression of CVID CD3+ PBMCs was enhanced to levels comparable to controls. Exogenous IL-15 resulted in further enhancement of anti-CD3-induced CD69 expression to a greater extent than that achieved with IL-2. A greater degree of apoptosis was found in CVID patients than controls following anti-CD3 stimulation (P = 0.001). IL-15 but not IL-2 further increased anti-CD3-induced apoptosis in control PBMCs (P = 0.001). In contrast, the degree of anti-CD3-induced apoptosis in CVID PBMCs was unaffected by IL-15 or IL-2. Addition of anti-Fas to cultures prestimulated with anti-CD3 further increased the apoptosis in control PBMCs but had no effect on apoptosis of CVID PBMCs.

CONCLUSION

Comparable anti-CD3-induced activation and enhanced apoptosis were observed in PBMCs from children with CVID compared with controls. The degree of apoptosis in CVID PBMCs was not affected by exogenous IL-15 or anti-Fas, suggesting a preactivated status in vivo.

Early activation of peripheral lymphocytes in human acute pancreatitis

BACKGROUND

The CD69 antigen is an indicator of early lymphocyte activation.

GOALS

To evaluate the early activation of peripheral lymphocytes T, B, and NK in patients with acute pancreatitis in comparison with patients with acute abdomen of nonpancreatic origin.

STUDY

Thirty patients with acute pancreatitis were studied; 20 of them had the mild form of the disease and 10 had the severe form. Thirty patients with nonpancreatic acute abdomen were used as controls. All patients were enrolled within 48 hours of the onset of pain. In all patients, leukocytes and total lymphocyte and lymphocyte subset counts (CD4+, CD8+, CD56+, CD19+, CD4+CD69+, CD8+CD69+, CD56+CD69+, CD19+CD69+) were determined upon hospital admission.

RESULTS

The percentage of total lymphocytes was significantly lower in acute pancreatitis patients than in those with nonpancreatic acute abdomen (P = 0.014); patients with severe pancreatitis had a percentage of total lymphocytes significantly lower when compared with patients with mild pancreatitis (P < 0.001). The CD19+CD69+ count was significantly lower in patients with severe pancreatitis (24.6 +/- 14.6%) than in patients with mild pancreatitis (46.7 +/- 16.5%; = 0.006). The counts of the other lymphocyte subsets were not statistically different between patients with acute pancreatitis and those with nonpancreatic acute abdomen, as well as between patients with mild and severe acute pancreatitis.

CONCLUSIONS

Patients with severe pancreatitis show impaired early activation of peripheral CD19+ cells.

Defective T-helper cell function after T-cell-depleting therapy affecting naive and memory populations

Impaired T-cell function after T-cell- depleting (TCD) therapy has been hypothesized to be related to a transient predominance of extrathymically expanding memory T cells. To test whether after TCD therapy the naive T-helper cell population is functionally intact, the in vitro immune response of CD4(+)CD45RA(+) (naive) and of CD4(+)CD45RA(-) (memory) cells to polyclonal mitogens (immobilized anti-CD3, phytohemagglutinin) was analyzed by flow cytometry in 22 pediatric patients after high-dose chemotherapy (including 5 after autologous and 5 after allogeneic stem cell support). At 1 to 3 months after TCD therapy, patient samples showing decreased lymphoproliferative responses also showed a reduced induction of the early activation marker CD69 by CD4(+) T cells from 4 to 72 hours after stimulation even when supplemented with exogenous interleukin-2. This defect affected CD4(+)CD45RA(-) cells, but, strikingly, also CD4(+)CD45RA(+) cells, including samples in which CD4(+)CD45RA(+) cells were more than 90/microL, thus indicating ongoing thymopoiesis. Histogram analyses showed the median peak channel of CD69 in control CD4(+)CD45RA(+) cells rising 98-fold (median) but only 28-fold in patient cells (P <.0001). Apoptosis as detected by annexin V staining was increased in resting patient CD4(+) T cells (25% versus 6%) and also affected CD4(+)CD45RA(+) cells (12% versus 5%, P <.01). When peripheral blood mononuclear cells (PBMCs) were enriched for T cells, stimulatory responses of CD4(+) cells and of CD4(+)CD45RA(+) cells markedly improved. Thus, after TCD therapy suppressor factors contained in the non-T-cell fraction of PBMCs may affect T-helper cells irrespective of their naive or memory phenotype thus extending T-cell dysfunction to the presumably thymus-dependently regenerated T cells.

HIV-1 infection impairs cell cycle progression of CD4(+) T cells without affecting early activation responses

Failure of CD4(+) T cells to proliferate in response to antigenic stimulation is a characteristic of HIV infection. Analysis of the proliferation defect has been hampered by an inability to identify CD4(+) cells with T cell receptor specificity for antigen. To focus only on cells that had been stimulated through the T cell receptor, CD4(+) T cells were stimulated with an anti-Vbeta3 Ab that activates approximately 3-5% of peripheral blood T cells. This approach revealed proliferation defects in cells from HIV-infected patients that were not appreciated using anti-CD3 Ab stimulation and provided the capacity to examine responses on a single cell basis. After anti-Vbeta3 Ab stimulation, CD4(+)Vbeta3(+) cells from HIV-infected patients demonstrated defects in expression of cell cycle-associated proteins, D-type cyclins, and cyclin A. However, the expression of early activation markers, CD69 and CD25, was not significantly impaired in cells from most patients. Thus, CD4(+) T cell proliferation failure in HIV disease is characterized by dysregulated activation that precludes cell cycle progression. This proliferation defect was most apparent in patients with diminished CD4(+) T cell numbers and higher plasma HIV RNA levels. CD4(+) T cell proliferation failure may be a key determinant of immune impairment in HIV disease.

Inhibition of natural killer cell cytotoxicity and interferon gamma production by the envelope protein of HIV and prevention by vasoactive intestinal peptide

Natural killer (NK) cell dysfunction is common in human immunodeficiency virus (HIV)-infected subjects, although its mechanisms are poorly understood. A direct effect of HIV envelope glycoprotein gp120 may be involved. We investigated the in vitro effects of gp120 on the major NK cell effector functions, natural cytotoxicity and cytokine production. In addition, the ability of the vasoactive intestinal peptide (VIP) to modulate these effects was investigated. Our results indicated that gp120 inhibits NK natural cytotoxicity and showed, for the first time, that the inhibition affects also the production of the proinflammatory cytokine interferon-gamma (IFN-gamma). Interestingly, the inhibitory effect on NK cell functions was obtained with gp120 at concentrations within the range measured in the serum of HIV-infected subjects. Furthermore, we showed that the inhibitory activity of gp120 can be prevented by coincubation with VIP, even if VIP has no stimulatory activity by itself. Taken together these data suggest that (1) an inhibitory effect of gp120 may account for the NK cell dysfunction in HIV-infected subjects; (2) the gp120-mediated decrease in IFN-gamma production by NK cells may contribute to the cytokine imbalance observed in HIV infection; and (3) VIP counteracts the inhibitory effect of gp120 on NK cell functions.

Assessment of donor T-cell function in cellular blood components by the CD69 induction assay: effects of storage, gamma radiation, and photochemical treatment

BACKGROUND

Functional donor T-lymphocytes in blood components may cause a variety of transfusion complications. A flow cytometric assay based on the measurement of induced CD69 expression may be an alternative to cell proliferation methods in determining the functional status of these cells in blood components.

STUDY DESIGN AND METHODS

Seven units of whole blood, RBCs, and platelet concentrates (PCs) were stored under blood bank conditions. Half of 3 PCs each were gamma-radiated or treated with UVA+psoralen; the other half served as controls. Samples were analyzed for phorbolester-induced expression of CD69 as an indicator of cell responsiveness and for exclusion of propidium iodide as a measure of cell membrane integrity and viability.

RESULTS

CD69 inducibility and propidium iodide exclusion decreased exponentially (half-life, 3. 3 and 8.1 days, respectively) during cold blood storage. Irradiation and UVA+psoralen treatment of PCs immediately reduced CD69 inducibility to 21 percent (controls, 82%; p = 0.004) and 12 percent (controls, 95%; p = 0.0008), respectively. The proportion of cells capable of propidium iodide exclusion was similar in treated samples and controls, but it declined faster in the treated samples during subsequent storage.

CONCLUSION

Flow cytometric measurement of CD69 induction can be adapted to provide quantitative assessment of T-cell function in blood components. Results obtained by the CD69 assay are in general agreement with those previously reported by use of proliferation methods; the assay may be useful for special applications in transfusion medicine.

Increased expression of the lymphocyte early activation marker CD69 in peripheral blood correlates with histologic evidence of cardiac allograft rejection

BACKGROUND

The human leukocyte membrane protein CD69 is an early activation marker induced in T lymphocytes, B cells, and natural killer cells in response to inflammatory stimuli. Cardiac catheterization and endomyocardial biopsy remain the "gold standard" for diagnosis of rejection after transplantation, and noninvasive methods of rejection surveillance have long been sought. We studied CD69 membrane protein expression in peripheral blood T lymphocytes obtained from pediatric cardiac transplant recipients at the time of biopsy and correlated the results with histologic rejection scores.

METHODS

Heparinized whole blood samples were obtained from pediatric cardiac transplant recipients at the time of cardiac biopsy, as well as from control subjects. Lymphocytes were labeled with antibodies for CD3, CD4, CD8, and CD69 and analysis performed using flow cytometric methods.

RESULTS

Resting CD69 expression (measured as a percentage of gated events) was significantly increased in patients with concurrent histologic evidence of rejection (International Society for Heart and Lung Transplantation grade > or =3A) when compared to those with minimal or no rejection and controls. Although statistically significant for both lymphocyte subsets, this relationship was more pronounced for CD8+ T cells (P<0.001) than for CD4+ T cells (P=0.001). When data were analyzed by rejection score, a percentage activation of the CD8+ subset (CD69+/CD8+ cells as a percentage of total gated events) exceeding 15% correlated with significant rejection.

CONCLUSIONS

Measurement of the expression of the early activation marker CD69 in peripheral blood lymphocytes by flow cytometry may provide a noninvasive means of assessing immune activation and possible rejection in cardiac transplant recipients.

Mitogen-induced T-cell CD69 expression is a less sensitive measure of T-cell function than [(3)H]-thymidine uptake

The most widely used in vitro measure of T-cell function has been the assessment of mitogen induced proliferation by [(3)H]-thymidine incorporation. Mitogens also induce T-cell surface expression of a number of molecules associated with activation, including CD69. Recent reports have suggested that flow cytometric analysis of CD69 expression may be a simpler and faster means of measuring T-cell function. Most studies have been on normal subjects, and the sensitivity of CD69 expression as an in vitro measure of clinical immunodeficiency remains unknown. We address this issue by concurrently measuring mitogen-stimulated T-cell CD69 expression and [(3)H]-thymidine incorporation in a normal population and five immunocompromised patients negative for the human immunodeficiency virus (HIV). All patients had recurrent infections and had known causes of immunodeficiency. Whole blood cultures were setup to measure phytohaemagglutinin A (PHA)- and superantigen staphylococcal enterotoxin B (SEB)-induced CD69 expression at 5, 24, and 72 h, and [(3)H]-thymidine incorporation at 72 h. All immunodeficient patients had lower than normal PHA responses and 3 of 4 had low SEB responses. However in 7 out of 8 of the patient tests, mitogen-induced T-cell CD69 expression was within the normal range. Similar results were found with CD4(+) T-cell CD69 expression. This study indicates that measurement of mitogen-induced T-cell CD69 expression lacks sensitivity in determining T-cell dysfunction in HIV-negative immunodeficient patients.

Viral load and CD69 molecule expression on freshly isolated and cultured mitogen-stimulated lymphocytes of children with perinatal HIV-1 infection

HIV-1 in adults changes the proportion of mitogen-stimulated lymphocytes expressing the CD69 activation molecule, but little is known about this molecule expression on lymphocytes of HIV-1-infected (HIV-1+) children. Freshly isolated CD3+, CD4+, CD8+ and CD19+ and phytohaemagglutinin (PHA)-stimulated CD3+, CD4+ and CD8+ lymphocytes co-expressing CD69 were investigated cross-sectionally (adopting a MoAb double-staining technique) in 24 HIV-1+ children with severe disease and given anti-retroviral therapy and in 24 age-matched healthy children. CD69 results in HIV-1+ children were correlated with plasma HIV-1 RNA load prospectively determined. HIV-1+ compared with healthy children had higher frequencies of freshly isolated CD3+CD69+ (2.4 +/- 2.2% versus 0.9 +/- 0.5%; P = 0.002) and CD8+CD69+ (1.5 +/- 1.1% versus 0. 5 +/- 0.2%; P < 0.0001) lymphocytes. The frequencies of CD4+CD69+ and CD19+CD69+ lymphocytes were similar. High viral load correlated with an elevated proportion of freshly isolated CD3+CD69+ and CD8+CD69+ lymphocytes. HIV-1+ children showed reduced frequencies of PHA-stimulated CD3+CD69+ (60.7 +/- 7.6% versus 86.1 +/- 7.6%; P < 0. 001), CD4+CD69+ (73.6 +/- 18.2% versus 92.6 +/- 5.1%; P < 0.001), and CD8+CD69+ (51.0 +/- 19.1% versus 65.3 +/- 15.4%; P = 0.007) lymphocytes. Virologic worsening within 6 months correlated with a low proportion of PHA-stimulated CD3+CD69+ and CD8+CD69+ lymphocytes. CD69 molecule expression reflected the coexistence of immune activation and immune deficiency in HIV-1 infection. Changes partly differed from those observed in HIV-1+ adults. CD8+CD69+ (but not CD4+CD69+) lymphocyte proportion correlated with virologic course, and an impaired ability of CD8+ lymphocytes to express CD69 upon PHA stimulation preceded a virologic worsening.

Early effects of antiretroviral combination therapy on activation, apoptosis and regeneration of T cells in HIV-1-infected children and adolescents

OBJECTIVES

To assess the relationship between apoptosis, activation and regeneration of T cells, and viral replication in paediatric patients with HIV-1 infection during antiretroviral therapy (ART).

DESIGN

In 15 HIV-1-positive children and adolescents sequential blood samples were obtained during 16 episodes of ART using combinations of nucleosidic HIV-1 reverse transcriptase (RT)-inhibitors and HIV-1 protease inhibitors or non-nucleosidic RT-inhibitors.

METHODS

We assessed sensitivity of freshly isolated peripheral blood T cells towards spontaneous, anti-CD95- and anti-CD3-induced apoptosis and activation before and after 6-8 weeks of ART. Expression of CD95, CD45RA, CD45RO and CD62L on CD4 and CD8 T cells and of CD34 on mononuclear cells was studied by multiparameter flow cytometry before and after 10-12 weeks of ART.

RESULTS

ART caused a significant increase in absolute lymphocyte and CD4 T cell counts (P < 0.03 and P < 0.02, respectively) and a decrease in both anti-CD95- and anti-CD3-induced apoptosis of CD4 and CD8 T cells to near normal levels even in patients without complete suppression of viral replication. A significant reduction in the percentage of CD95 (but not of CD95high) CD4 T cells was observed (P < 0.005). Resting/naive cells contributed significantly (P < 0.03) to the rise in CD4 T cells especially in infants and young children.

CONCLUSIONS

Different mechanisms may contribute to early T cell reconstitution in HIV-1-infected children and adolescents during ART: decreased activation-induced apoptosis leading to increased survival of circulating primed/memory T cells; decreased activation-induced naive-to-memory shift increasing the frequency of circulating resting/naive T cells; increased input of haematopoietic progenitor cells from the bone marrow into the thymus and decreased intrathymic T cell death leading to an increased thymic output of naive T cells.

T lymphocyte cytokine profile at a single cell level in alveolar Echinococcosis

The metacestode Echinococcus multilocularis causes a life-threatening disease in humans, named alveolar echinococcosis (AE). A comparative analysis of the early activation marker CD69 on peripheral blood mononuclear cells (PBMC) of patients with AE and healthy controls after in vitro culture with crude E. multilocularis antigen revealed that specific expression of CD69 was induced in CD4(+)T lymphocytes as well as in CD8(+)T lymphocytes. Using a protocol for intracellular staining of cytokines followed by fluorescence activating cell sorting (FACS) analysis, production of interleukin (IL)-2, IL-5 and IL-10 was detected in CD4(+)as well as in CD8(+)lymphocytes. Most notably, there was a definite increase in the expression of IL-10 in CD8(+) lymphocytes from patients with alveolar echinococcosis. The data support an important role of CD8(+) lymphocytes in the long persistence of the metacestode.

Cell cycle arrest during measles virus infection: a G0-like block leads to suppression of retinoblastoma protein expression

One of the major mechanisms by which measles virus (MV) infection causes disease and death is suppression of the immune response. The nonresponsiveness of MV-infected human lymphocytes to mitogens and a partial block in the G0/G1 phase of the cell cycle observed in vitro is thought to reflect in vivo immunosuppression. In order to molecularly dissect MV-induced immunosuppression, we analyzed expression of surface activation markers and cell cycle-regulatory proteins in MV-infected human T lymphocytes. MV Edmonston (MV-Ed) could induce and maintain a high level of the early activation marker CD69 in the absence of proliferation. Expression of cyclins D3 and E, which positively control entry into S phase, was also significantly decreased. Analysis of inhibitors of progression into S phase showed that a high level of p27 was maintained in the G0/G1-blocked subpopulation of MV-Ed-infected cells compared to the proliferating MV-infected cells. Furthermore, cell cycle-related upregulation of retinoblastoma (Rb) protein synthesis did not occur in the MV-Ed-infected lymphocytes. Acridine orange staining, which distinguishes cells in G0 from cells in G1, showed that RNA levels were not upregulated following activation, which is consistent with cells remaining in a G0 state. Although expression of surface activation markers indicated entry into the cycle, intracellular Rb and RNA levels suggested a quiescent state. These results indicate that MV can uncouple activation of T lymphocytes from transition of G0 to G1.

Donor cell induced CD69 expression and intracellular IL-2 and IL-4 production by peripheral blood lymphocytes isolated from kidney transplant recipients

Flow cytometry assays, which measure CD69 activation and intracellular cytokine production, have been used to measure peripheral blood lymphocyte (PBL) responses to in vitro antigen exposure. In the present study, we show that, in healthy individuals and immunosuppressed kidney transplant recipients, CD69 expression and intracellular cytokine production by peripheral blood T cells compare favorably to thymidine uptake as a measure of PBL response to alloantigen in mixed leukocyte culture (MLC). Heparinized whole blood from 23 healthy individuals was incubated for 24-48 h with 3rd party allogeneic monocytes; blood from twelve kidney transplant recipients was incubated with monocytes from their kidney donor and with monocytes from unrelated individuals. The percentage of T cells expressing surface CD69 or intracellular IL-2 or IL-4 was determined by 3-color flow cytometry. We identified 5 donor-specific response patterns in our kidney transplant group. One transplant recipient was hyporesponsive; his cells did not express CD69 or produce IL-2 in response to either donor or 3rd party allogeneic cells. All other transplant recipients expressed CD69 and IL-2 in response to 3rd party allogeneic cells. Two had no response to donor cells (donor-specific hyporesponsiveness), three had donor-specific anergy (CD69 expression without cytokine production in response to donor cells), five had a donor-specific Thl response (CD69 expression and IL-2 production in response to donor cells), and one had a donor-specific Th2 response (CD69 expression and IL-4 but not IL-2 production in response to donor cells). Rapid measures of donor-specific hyporesponsiveness such as CD69 activation antigen expression and intracellular cytokine production may prove valuable in monitoring lymphocyte function and aid in the long-term management of kidney transplant recipients.

The influence of surgical stress on T cells: enhancement of early phase lymphocyte activation

For the control of postoperative infection, it may be important to understand the possible influences of surgical stress on the host immune system. To this end, we examined how the early phase of lymphocyte activation was affected in patients after major surgery (eight patients with esophageal carcinoma and six undergoing cardiac surgery) using a flow cytometric assay based on expression of the early activation antigen, CD69. Freshly isolated T cell in preoperative and postoperative samples did not express CD69. When peripheral blood mononuclear cells were stimulated in vitro, the expression of CD69 was greatly enhanced in both CD4 and CD8 T cells, compared with the preoperative samples. The proportion of de novo CD69-expressing cells in the CD4 subset was approximately 3 times (Postoperative Day 1) and 4 times (Postoperative Days 2, 3, 5, and 7) greater than those preoperatively, whereas the proportion of de novo CD69-expressing cells in the CD8 subset was approximately 1.5 times (Postoperative Days 2 and 5) and 2 times (Postoperative Day 3) greater than those preoperatively. The proportion of CD69+ cells was significantly greater in the CD4+ subset than in the CD8+ subset during the postoperative period.

IMPLICATIONS

Our results show that major surgical stress enhances the early phase of lymphocyte activation. The augmentation of activation was greater in CD4 (helper) T cells than in CD8 (cytotoxic) T cells.

Expression of the activation antigen CD69 predicts functionality of in vitro expanded peripheral blood mononuclear cells (PBMC) from healthy donors and HIV-infected patients

Gene therapy for AIDS necessitates harvest and expansion of PBMC from HIV-infected patients. We expanded PBMC from healthy blood donors and HIV-infected patients for up to 14 days using four expansion protocols: 3 days of phytohaemagglutinin (PHA) stimulation, continuous PHA stimulation, 3 days of stimulation with anti-CD3 and anti-CD28, and continuous stimulation with anti-CD3 and anti-CD28. Functionality of PBMC was evaluated prior to and after expansion using standard proliferation assay. Phenotype and lymphocyte subset activation defined by expression of CD69 and CD25 were determined using flow cytometry. PBMC from healthy donors and HIV-infected patients were readily expanded. The best expansion was obtained using stimulation for 3 days. After expansion, functionality of PBMC measured as proliferative response was partly conserved. PBMC expanded with stimulation for 3 days exhibited more preserved functionality than PBMC stimulated continuously (P < 0.03). The mean proliferative response in each of the four different expansion protocols correlated with the mean values of CD69 expression. The proliferative responses from patients and healthy donors expanded with PHA stimulation for 3 days correlated with CD69 expression on CD4 cells (r = 0.68, P < 0.01) and on CD8 cells (r = 0.59, P < 0.03). Furthermore, expression of CD69 reliably predicted which patients and donors had highly conserved functionality after in vitro expansion. Finally, PBMC expanded with PHA stimulation for 3 days were examined for apoptosis. Only a minor fraction was primed for apoptosis, and this fraction could be significantly reduced by addition of IL-2 to the culture medium (P < 0.05). In conclusion, the feasibility of expanding PBMC from HIV patients was demonstrated. Expanded PBMC had conserved functionality. Finally, after in vitro expansion, expression of the activation antigen CD69 reliably predicted functionality of PBMC.

A whole-blood assay for qualitative and semiquantitative measurements of CD69 surface expression on CD4 and CD8 T lymphocytes using flow cytometry

A whole-blood flow cytometry-based assay was utilized to assess CD4 and CD8 T-lymphocyte activation in response to phytohemagglutinin (PHA) stimulation. T-lymphocyte activation was assessed by qualitative (percent CD69) and semiquantitative (anti-CD69 antibody binding capacity) measurements of CD69 surface expression. Whole-blood samples from 21 healthy and 21 human immunodeficiency virus (HIV)-infected (<500 absolute CD4 counts per mm3) individuals were stimulated with 20 microg of PHA per ml for 18 to 24 h. The proportions of activated CD4 and CD8 T lymphocytes expressing CD69 (percent CD69) and the levels of CD69 expression on each T-lymphocyte subset (anti-CD69 antibody binding capacity) were measured. By using this assay system, T-lymphocyte activation was impaired in both CD4 and CD8 T-lymphocyte subsets of HIV-infected individuals. The proportions of CD69-positive CD4 and CD8 T lymphocytes were 43 and 27% lower, respectively, in samples from HIV-infected individuals compared to samples from healthy individuals. Similarly, the levels of CD69 expression on each activated CD4 and CD8 T-lymphocyte subset were 48 and 51% lower, respectively. These results suggest that both qualitative and semiquantitative measurements of CD69 surface expression by flow cytometry can be used to assess T-lymphocyte activation.

In vitro cellular and cytokine responses to mycobacterial antigens: application to diagnosis of tuberculosis infection and assessment of response to mycobacterial vaccines

Mycobacterial infection leads to the development of specific cell-mediated immune responses that have been measured clinically by assessing delayed-type hypersensitivity with Mantoux skin testing. Several characteristics of Mantoux skin testing for tuberculosis infection can make the procedure inaccurate, inconvenient, and sometimes misleading. It is also a poor predictor of immunity to tuberculosis in bacille Calmette-Gúerin vaccinees, yet decisions to revaccinate often are based on skin test responses after initial immunization. Skin testing with other mycobacterial antigens has similar limitations. In vitro assessment of cellular immunity to mycobacteria offers multiple, potential advantages over skin testing and has become technically feasible in recent years. Measurement of the effector functions that comprise cell-mediated immunity (eg, cytokine secretion and cytotoxicity) rather than cutaneous delayed-type hypersensitivity responses is more likely to reflect meaningfully specific mycobacterial immunity and, therefore, provide a means for determining mycobacterial immunity after immunization. Eliminating the variability in placement and interpretation inherent in skin testing could provide a more stable foundation for comparative studies in populations and improve decision making for individuals. Finally, in vitro testing permits the use of discrete mycobacterial antigens instead of crude protein preparations, allowing greater specificity in the detection of infection as well as assessment of responses to defined candidate vaccine antigens. Several studies have compared skin testing with in vitro proliferation of lymphocytes stimulated by mycobacterial antigens for the detection of Mycobacterium tuberculosis infection. Preliminary veterinary and human studies suggest that in vitro assessment of gamma-interferon production in response to mycobacterial antigens can be used to detect prior infection with organisms of the M tuberculosis complex. Streamlined techniques for in vitro testing of cellular immunity may allow its practical adoption in the clinical setting and lead to its use as a replacement for Mantoux skin testing.

T cells from individuals in advanced stages of HIV-1 infection do not proliferate but express activation antigens in response to HIV-1-specific antigens

Like T cells from healthy subjects, those of HIV-1-infected patients are capable of expressing activation antigens on their surface after antigenic or mitogenic stimulation, but their proliferative activity is strongly reduced or even absent, especially in patients with advanced stages of the disease. The characteristic of expressing activation antigens in response to different stimuli in the absence of cell proliferation is shared by CD4+ and CD8+ T-cell subsets from HIV-1-infected patients. The number of T cells capable of expressing CD25 and CD71 in response to HIV-1-related antigens but not of proliferating increased significantly with the progression of the disease, but the number of T cells capable of expressing the two activation antigens in response to the classic tetanus toxoid recall antigen decreased. The higher numbers of T cells capable of responding to HIV-1-related antigens in conjunction with a reduction in the number of T cells responding to recall antigens may explain the occurrence of different infections, including opportunistic microorganisms, during the more advanced stages of HIV-1 infection. Because the increase in the number of HIV-1 antigen-responding T cells (defined by CD25 and CD71 activation antigen expression) is a characteristic of symptomatic HIV-1-infected patients, expression (by flow cytometry) of these activation antigens on T cells in response to HIV-1 antigens could be used as a new marker of disease progression.

CD69 expression reliably predicts the anti-CD3-induced proliferative response of lymphocytes from human immunodeficiency virus type 1-infected patients

Published studies suggest that mitogenic responses of lymphocytes can be reliably assessed by monitoring the expression of lymphocyte surface CD69 after 24 h of culture with the stimulant. We tested this hypothesis by determining the ability of lymphocyte CD69 expression to predict the outcome (normal or abnormal) of lymphocyte proliferative responses to anti-CD3 in a group of human immunodeficiency virus type 1 (HIV-1)-infected patients (n = 47). Cutoff values for defining normal and abnormal CD69 expression and proliferative ([3H]thymidine incorporation) responses were established with lymphocytes from healthy uninfected controls (n = 20). Lymphocytes from 29 HIV-infected patients exhibited an abnormal proliferative response, and those from 25 of the 29 also exhibited abnormal CD69 expression (sensitivity, 86.2%). Similarly, lymphocytes from 18 HIV-infected patients exhibited a normal proliferative response, and those from 16 of the 18 also exhibited normal CD69 expression (specificity, 88.9%). The predictive value of a normal CD69 result was 80%, and the predictive value of an abnormal CD69 result was 92.6%. These findings demonstrate that HIV-1-associated impairments in lymphocyte activation can be reliably detected by the rapid and nonradioactive CD69 expression assay.