ELISpot: a new tool for the detection of nickel sensitization

Memory T helper cells identify patients with nickel, cobalt, and chromium metal allergy

BACKGROUND

Patch testing is the gold standard for identifying culprit allergens in allergic contact dermatitis; however, it is laborious and positive reactions are difficult to quantitate. Development of complementary in vitro tests is, therefore, of great importance.

OBJECTIVES

This study aimed to improve the in vitro lymphocyte proliferation test (LPT) to detect allergic responses to nickel (Ni), cobalt (Co), and chromium (Cr).

METHODS

Twenty-one metal allergic patients with a positive patch test to Ni (n=16), Co (n=8), and Cr (n=3) and 13 controls were included. All were tested by a flow cytometric LPT.

RESULTS

Metal-reactive cells were identified as T helper (Th) cells with high expression of the memory marker CD45RO. Skin-homing (cutaneous lymphocyte-associated antigen positive [CLA+]) Ni-reactive memory Th (Th_mem ^hi ) cells identified individuals with a positive patch test for Ni with 100% sensitivity (95% confidence interval [CI] 81%-100%) and 92% specificity (95% CI 67%-100%). Moreover, Co-specific Th_mem ^hi cells expressing CCR6 identified patients with a positive patch test for Co with 63% sensitivity (95% CI 31%-86%) and 100% specificity (95% CI 77%-100%). In Cr allergic individuals, Cr-reactive Th_mem ^hi cells tended to increased CLA and CCR6 expression.

CONCLUSION

Metal-reactive Th cells with high expression of CD45RO and coexpression of CLA and CCR6 improved the LPT, making it an attractive supplement to the patch test.

TCRs with segment TRAV9-2 or a CDR3 histidine are overrepresented among nickel-specific CD4+ T cells

BACKGROUND

Nickel is the most frequent cause of T cell-mediated allergic contact dermatitis worldwide. In vitro, CD4+ T cells from all donors respond to nickel but the involved αβ T cell receptor (TCR) repertoire has not been comprehensively analyzed.

METHODS

We introduce CD154 (CD40L) upregulation as a fast, unbiased, and quantitative method to detect nickel-specific CD4+ T cells ex vivo in blood of clinically characterized allergic and non allergic donors. Naïve (CCR7+ CD45RA+) and memory (not naïve) CD154+ CD4+ T cells were analyzed by flow cytometry after 5 hours of stimulation with 200 µmol/L NiSO₄ ., TCR α- and β-chains of sorted nickel-specific and control cells were studied by high-throughput sequencing.

RESULTS

Stimulation of PBMCs with NiSO₄ induced CD154 expression on ~0.1% (mean) of naïve and memory CD4+ T cells. In allergic donors with recent positive patch test, memory frequencies further increased ~13-fold and were associated with markers of in vivo activation. CD154 expression was TCR-mediated since single clones could be specifically restimulated. Among nickel-specific CD4+ T cells of allergic and non allergic donors, TCRs expressing the α-chain segment TRAV9-2 or a histidine in their α- or β-chain complementarity determining region 3 (CDR3) were highly overrepresented.

CONCLUSIONS

Induced CD154 expression represents a reliable method to study nickel-specific CD4+ T cells. TCRs with particular features respond in all donors, while strongly increased blood frequencies indicate nickel allergy for some donors. Our approach may be extended to other contact allergens for the further development of diagnostic and predictive in vitro tests.

The Allergic Bone Marrow? The Immuno-Capacity of the Human Bone Marrow in Context of Metal-Associated Hypersensitivity Reactions

Arthroplasty ranks among the greatest achievements of surgical medicine, with total hip replacement termed “the operation of the century.” Despite its wide success, arthroplasty bears risks, such as local reactions to implant derived wear and corrosion products. Prevalence of allergies across Western society increases and along the number of reported hypersensitivity reactions to orthopedic implant materials. In this context the main focus is on delayed hypersensitivity (DTH). This mechanism is mainly attributed to T cells and an overreaction of the adaptive immune system. Arthroplasty implant materials are in direct contact with bone marrow (BM), which is discussed as a secondary lymphoid organ. However, the mechanisms of sensitization toward implant wear remain elusive. Nickel and cobalt ions can form haptens with native peptides to activate immune cell receptors and are therefore common T helper allergens in cutaneous DTH. The rising prevalence of metal-related allergy in the general population and evidence for the immune-modulating function of BM allow for the assumption hypersensitivity reactions could occur in peri-implant BM. There is evidence that pro-inflammatory factors released during DTH reactions enhance osteoclast activity and inhibit osteoblast function, an imbalance characteristic for osteolysis. Even though some mechanisms are understood, hypersensitivity has remained a diagnosis of exclusion. This review aims to summarize current views on the pathomechanism of DTH in arthroplasty with emphasis on BM and discusses recent advances and future directions for basic research and clinical diagnostics.

Lymphocyte function following radioiodine therapy in patients with thyroid carcinoma

Aim: Since the nuclear disaster in Fukushima has raised great concern about the danger of radioactivity, we here addressed the question if the therapeutic use of iodine 131, the most frequently applied radionuclide, was harmful to immune function in patients. It was our aim to define for the first time in a clinical setting how radioiodine therapy alters anti-microbial immune responses. Patients, methods: In 21 patients with thyroid carcinoma anti-microbial lymphocyte responses were assessed by lymphocyte transformation test and ELISpot – measuring lymphocyte proliferation and on a single cell level production of pro- and anti-inflammatory cytokines (interferon-γ and interleukin- 10) – prior to therapy, at day 1 and day 7 post therapy. Results: Proliferative lymphocyte responses and interferon-γ production after in vitro stimulation with microbial antigens were significantly (p < 0.05) increased at day 1 vs. pre therapy, and returned to pre therapy levels at day 7. On the contrary, at day 1 interleukin-10 production was significantly (p < 0.05) reduced. Thus, we observed a short-term increase in pro-inflammatory immune responses. However, T lymphocyte responses were in the range of healthy controls at all three time points. Conclusion: Thyroid carcinoma patients receiving radioiodine therapy do not display any sign of immunosuppression.

Ex vivo assessment of cellular immune function - applications in patient care and clinical studies

Cellular ex vivo assays have a broad range of applications in patient care and clinical studies, especially when they are standardized and highly sensitive. As compared to analyses by molecular genetics such as the single nucleotide polymorphism (SNP) testing, they are usually more global. These assays partly mimic the in vivo situation, relying on a complex interaction of various immune cells. For example, they can be used to determine modulation of alloresponses by treatment or underlying disease, diagnose and quantify primary and secondary cellular immunodeficiency, follow-up vaccination responses, measure adoptive transfer of virus-specific immunity via hematopoietic stem cell or liver transplantation, assess allergy, antimicrobial immunity and also rare effector/memory cells directed against tumor antigens. This review will first shortly describe various cellular in vitro methods and then present applications, summarizing some own studies performed within the last 18 years.

A laboratory test based on determination of cytokine profiles: a promising assay to identify exposition to contact allergens and predict the clinical outcome in occupational allergic contact dermatitis

Background

Para-phenylenediamine (PPD) is the main allergen causing adverse reactions to hair dyes and a frequent cause of occupational-related skin sensitization among hairdressers and beauticians. The immunologic mechanism of the disease relies on the production of inflammatory cytokines by allergen-specific T cells, while regulatory T cells are thought to down-modulate the allergic response. This study was aimed at investigating the expression of effector or regulatory cytokines in exposed subjects in order to verify whether different cytokine profiles might predict distinct clinical outcomes. Peripheral blood mononuclear cells (PBMC) from 21 subjects occupationally exposed or not (10) to PPD were kept in short term cultures in the presence of optimized concentrations of NiSO4 × 6H2O or PPD. The production of IFN-γ and IL-10 elicited by antigens were analyzed by the ELISpot assay.

Results

The presence of IFN-γ responses toward PPD was significantly correlated with a positive patch test (P = 0.002) and allergic symptoms, while IL10 responses were invariably found in PPD-exposed but clinically asymptomatic subjects with negative patch testing. We found concordance between the different cytokine profiles and patch test results. No false-positive results were found for the different cytokine profiles induced by PPD, resulting in 100% specificity. The sensitivity of the test was 87.5% (95% CI 65.9-100.0) with an overall test accuracy of 93.3%. Although larger prospective-retrospective studies are necessary to validate the predictive potential of the test, the negative and positive predicted values for PPD in this study were NPV = 87.5% and PPV = 100%, respectively.

Conclusions

These data indicate that distinct cytokine profiles are associated with different clinical manifestations. The test, which is based on a simple and rapid profiling of cytokine responses by T lymphocytes against allergens, has proven to be a promising laboratory tool, useful for both the identification of previous contact with allergens and the etiologic diagnosis of contact allergies as well as capable of predicting the clinical outcome (development of an allergic or tolerant response).

Expression of NTRK1/TrkA affects immunogenicity of neuroblastoma cells

High levels of the NTRK1/TrkA receptor are expressed in low-stage neuroblastomas, which are characterized by a good patient prognosis and often undergo spontaneous regression. In addition to apoptosis, tumor-immune responses might contribute to this regression. We hypothesized that TrkA expression might enhance the immune response to neuroblastomas. Immunohistochemistry on neuroblastoma tissue microarrays confirmed significantly higher lymphocyte infiltration in low-stage compared with high-stage tumors. Flow cytometry of human SH-SY5Y cells stably transfected with NTRK1/TrkA cDNA revealed significant upregulation of major histocompatibility complex (MHC) class I complexes on TrkA-expressing cells. Corresponding to this upregulation, T cell activity and cytoxicity was enhanced in the presence of SY5Y-TrkA cells or by medium conditioned by them, suggesting the existence of additional soluble factors stimulating the T cell response. Activation of natural killer (NK) cells was only increased in the presence of SY5Y-TrkA conditioned medium (CM) and not in co-culture assays, suggesting a dominant inhibitory effect of upregulated MHC class I as the primary NK cell escape mechanism of TrkA-expressing neuroblastomas. We reanalyzed gene expression data obtained from the cell culture model to identify additional genes involved in the TrkA-mediated modulation of immune responses. Upregulation of selected target genes in SY5Y-TrkA cells was confirmed on transcript and protein levels. However, none of the proteins were detected in medium conditioned by SY5Y-TrkA cells, arguing against these factors as soluble mediators of the TrkA-induced immune response. We here provide evidence that TrkA expression in neuroblastoma leads to an increased immunogenicity that may contribute to a less malignant phenotype and/or spontaneous regression of neuroblastoma cells.

Association of CD69 up-regulation on CD4+ Cla+ T cells versus patch test, strip patch test and clinical history in nickel sensitization

Objective

The patch test (PT) with its modification - the strip patch test (SPT) - is the standard in vivo procedure to diagnose an allergic contact dermatitis (ACD). To date, none of the in vitro tests for the diagnosis of ACD fulfils the requirements of an easy, valid and reliable test. To investigate the prediction ability of a flow cytometric assay of CD69 up-regulation on CD4+ CLA+ T cells in nickel-sensitive and non-nickel-sensitive patients.

Methods

In a prospective, investigator-blinded, clinical study a total of 85 nickel-sensitive (n = 44; 51.8%) and non-nickel-sensitive patients (n = 41; 48.2%) were enrolled. The association between CD69 up-regulation on CD4+ CLA+ T cells on the one hand and PT, SPT, and clinical history on the other hand was measured. Association is expressed with c statistic values (receiver operating characteristic analysis) and corresponding 95% CIs.

Results

The associations were c = 0.57 (95% CI: 0.42-0.72) between CD69 up-regulation and PT, c = 0.49 (95% CI: 0.36-0.62) between CD69 up-regulation and SPT, and c = 0.51 (95% CI: 0.37-0.64) between CD69 up-regulation and clinical history.

Conclusions

CD69 up-regulation on CD4+ CLA+ T cells in vitro could not predict neither a positive PT or SPT result nor a positive clinical history to nickel sulfate. The combination of clinical history and patch testing still remains the basis for diagnosing ACD.

Nickel, palladium and rhodium induced IFN-gamma and IL-10 production as assessed by in vitro ELISpot-analysis in contact dermatitis patients

BACKGROUND

Recent attempts to diminish nickel use in most industrial products have led to an increasing utilization of alternative metal compounds for destinations such as the alloys used in orthopaedics, jewellery and dentistry. The present study was undertaken with the aim to evaluate the potential for an allergic response to nickel, palladium and rhodium on the basis of antigen-specific induction of inflammatory/regulatory cytokines, and to characterize, according to the cytokine profiles, the nature of simultaneous positive patch tests elicited in vivo. Peripheral blood mononuclear cells (PBMC) from 40 patients with different patch test results were kept in short term cultures in the presence of optimized concentrations of NiSO4 x 6H2O, PdCl2 and Rh(CH3COO)2. The production of IFN-gamma and IL-10 elicited by metal compounds were analyzed by the ELISpot assay.

RESULTS

We found a specific IFN-gamma response by PBMC upon in vitro stimulation with nickel or palladium in well recognized allergic individuals. All controls with a negative patch test to a metal salt showed an in vitro IL-10 response and not IFN-gamma production when challenged with the same compound. Interestingly, all subjects with positive patch test to both nickel and palladium (group 3) showed an in vitro response characterized by the release of IFN-gamma after nickel stimulation and production of IL-10 in response to palladium.

CONCLUSION

These results strongly suggest that the different cytokine profiles elicited in vitro reflect different immune responses which may lead to the control of the allergic responses or to symptomatic allergic contact dermatitis. The development of sensitive and specific in vitro assays based on the determination of the cytokine profiles in response to contact allergens may have important diagnostic and prognostic implications and may prove extremely useful in complementing the diagnostic limits of traditional patch testing.

Cellular and humoral immune response to a third generation hepatitis B vaccine

Liver transplantation is often the ultimate option of therapy for chronically hepatitis B virus (HBV) infected patients. Adoptive transfer of HBV immunity with the liver after vaccination of living liver donors (LLD) could be a new approach to prevent reinfection in the recipients. The time to achieve HBV immunity in LLD is usually short (1-2 months). Therefore, we established a short time immunization protocol (four injections in 2 weeks intervals) using Hepimmune, a recombinant vaccine that contains the L, M and S proteins of HBV. We examined cellular and humoral immune responses after immunization with Hepimmune and compared its immunogenicity to that of a standard HBV vaccine containing only the S protein (HBVAXPRO). Cellular immunity was measured by interferon (IFN)-gamma ELISpot and proliferation assay. HBV-specific T cells were detectable in the Hepimmune group after the second and in the standard group after the third vaccination. IFN-gamma production of T cells was significantly higher (P < 0.001) after the third vaccination with Hepimmune. Proliferative responses were also significantly (P < 0.01) higher in the Hepimmune group after the second to fourth vaccination. The humoral immune response could already be detected after the first immunization in nine of 15 Hepimmune vaccinated test persons while it was only observed in one of 15 probands of the later group. Titres differed significantly (P < 0.01) following all four vaccinations. Thus, Hepimmune appears to be a good candidate for short time immunization protocols.

Allergic contact dermatitis to nickel: modified in vitro test protocols for better detection of allergen-specific response

To date, no in vitro test is suitable for routine diagnosis of contact allergy. The aim of our study was to establish improved in vitro test protocol for the detection of antigen-specific responses of lymphocytes from patients with allergic contact dermatitis to nickel (Ni-ACD). Blood leucocytes from 14 Ni-ACD patients and 14 controls were cultured in the presence of 'cytokine cocktails' skewing lymphocytes towards 'type 1' [interferon-gamma (IFN-gamma)-secreting] or 'type 2' [interleukin (IL)-5 and IL-13-secreting] phenotypes. The cocktails consisted of IL-7 and, respectively, either IL-12 or IL-4. Cell responses to nickel were measured with enzyme-linked immunospot assay (ELISpot), enzyme-linked immunosorbent assay (ELISA), and lymphocyte proliferation test (LPT). Significant differences between patients with Ni-ACD and controls were found for the 'type 2' cytokines IL-13 and IL-5, with further increase of allergen-specific responses occurring when cultures were supplemented with IL-7 and IL-4. No significant differences were found for IFN-gamma. The best correlate to clinical diagnosis was LPT with 'type 2' skewing (r= 0.739, P < 0.001), followed by IL-13 ELISpot with 'type 2' skewing (r= 0.654, P < 0.001). The non-radioactive method that correlated best with LPT was IL-2 ELISpot (r= 0.809, P < 0.001). Overall, we conclude that combining ELISpot assay with proposed modifications of culture conditions improves detection of specific lymphocyte responses in contact allergy to nickel.

Donor cell reaction to OKT3 as predictor of chronic graft-vs-host disease in hematopoietic stem cell recipients

OBJECTIVE

In the hematopoietic stem cell transplantation setting, granulocyte colony-stimulating factor (G-CSF) administration can reduce donor cell reactivity in vitro, but the clinical significance of this phenomenon was only sparsely defined.

METHODS

We performed lymphocyte transformation tests in 28 related stem cell donors pre and 5 days post G-CSF treatment, respectively, and correlated proliferative responses of donor peripheral blood mononuclear cells with clinical parameters in the corresponding recipients.

RESULTS

In vitro reactions towards 4 mitogens and 12 recall antigens at day 5 post G-CSF administration were predictive for the occurrence of chronic graft-vs-host disease (cGVHD). Here, proliferative responses towards the mitogen anti-CD3 monoclonal antibody (OKT3) above median were most informative; this threshold could be determined by discrimination and receiver operating curve (ROC) analyses. In the whole cohort (18 human leukocyte antigen [HLA]-identical and 10 partially mismatched donor-recipient pairs), OKT3 responses predicted cGVHD with an odds ratio of 33.0, a sensitivity of 79%, and a specificity of 90%. A subgroup analysis of HLA-identical pairs even yielded an odds ratio of 85.0. Furthermore, bivariate analysis defined HLA compatibility and responses towards OKT3 as independent risk factors for cGVHD (p = 0.02 and p = 0.0007, respectively).

CONCLUSION

The proliferative capacity of G-CSF-mobilized donor cells appears as a graft factor that determines the future incidence of cGVHD in the corresponding recipient.

[In vitro testing for allergic contact dermatitis]

Patch testing is the standard method to identify allergic contact dermatitis. Simple, safe and accurate in vitro methods identifying contact allergies would offer both theoretical and practical advantages. Using the lymphocyte transformation test (LTT), allergen-specific lymphocytes central to the pathogenesis of Type IV allergies can be identified. Various studies have assessed the value of LTT in the diagnosis of contact allergies. The current assessment is that the test can be helpful in distinguishing between irritant and allergic reactions. LTT is especially useful in demonstrating drug allergies and can also be employed to prove sensitization to gases or toxic substances. At the present time, it is not an alternative for patch testing in daily practice.

ELISpot assay as a sensitive tool to detect cellular immunity following influenza vaccination in kidney transplant recipients

Enhanced cellular immunity following influenza vaccination has been undetectable in kidney transplant recipients so far. Protection from influenza is dependent on cellular and humoral immunity. Aim of the study was to investigate immune responses before and after vaccination with influenza A and B antigens in 65 kidney transplant recipients. A significant increase in proliferative responses was only observed towards influenza B (P < 0.0001) by lymphocyte transformation test. The enzyme-linked immunospot (ELISpot) assay was more sensitive and detected significant, 3- to 5-fold increases (P < 0.0001) in interferon-gamma secretion using influenza A and B antigens. Furthermore, influenza antibody titers increased significantly (P < 0.0001). At month 1 post-vaccination 85% of patients displayed specific cellular, and 95% or 92% humoral immunity against influenza A and B, respectively. Thus, applying the sensitive ELISpot assay, influenza-specific cellular immunity could be detected for the first time in kidney transplant recipients after vaccination.

Nickel-induced IL-10 down-regulates Th1- but not Th2-type cytokine responses to the contact allergen nickel

Whereas the involvement of Th1- and Th2-type cytokines in contact allergy to nickel (Ni) is well documented, the role of the regulatory cytokine IL-10 is less clear. We therefore investigated the impact of IL-10 on Ni-induced Th1- (IFN-gamma) and Th2-type (IL-4 and IL-13) cytokine responses in human peripheral blood mononuclear cells (PBMC). PBMC from 15 blood donors with reactivity to Ni (Ni-PBMC) and 8 control donors devoid of reactivity (control PBMC) were stimulated with Ni and the frequency of cytokine-producing cells and the levels of secreted cytokines were analysed by ELISpot (IL-4, IL-13 and IFN-gamma) and ELISA (IL-10, IL-13 and IFN-gamma), respectively. The Ni-induced response was further assessed in the presence of recombinant IL-10 (rIL-10) or neutralizing antibody to IL-10 and the phenotype of the Ni-specific cytokine-producing cells regulated by IL-10 was determined by cell depletion experiments. Ni induced IL-10 production in Ni-PBMC (mean, (range); 33.1 pg/ml (0-93.4 pg/ml)) but not control PBMC (2.2 pg/ml (0-14.9 pg/ml)) (P = 0.002). Ni also induced significant production of IL-4, IL-13 and IFN-gamma that correlated with the IL-10 response. Addition of rIL-10 down-regulated the Ni-induced production of all cytokines but with a more pronounced effect on IFN-gamma. However, neutralization of Ni-induced IL-10 enhanced the levels of IFN-gamma induced by Ni (P = 0.004) but did not affect the number of IFN-gamma-producing cells or the production of other cytokines. Cell depletion experiments suggested that the Ni-specific IFN-gamma (and Th2-type cytokine) producing cells were CD4(+) T cells. The impact of IL-10 on Ni-induced IFN-gamma responses by CD4(+) T cells suggests that an important role of IL-10 in vivo is to counteract the allergic reactions mediated by Th1-type cytokines.

Nickel Elicits Concomitant and Correlated in vitro Production of Th1-, Th2-Type and Regulatory Cytokines in Subjects with Contact Allergy to Nickel

Nickel (Ni2+) elicits production of functionally distinct cytokines in vitro, but the relation between the cytokine profile and the degree of the allergic reaction in vivo needs to be better defined in order to improve the understanding of the immunological mechanisms involved in contact allergy and to facilitate development of in vitro diagnostics. The aim of the study was to define Th1-type [interferon-gamma (IFN-gamma)], Th2-type [interleukin-4 (IL-4), IL-5 and IL-13] and regulatory (IL-10) cytokine responses to Ni2+ in peripheral blood mononuclear cells (PBMC) from subjects with varying patch test reactivity to Ni2+. The study included subjects with strong (+3), moderate (+2), weak (+1) or negative (controls) patch test reactivity to Ni2+ (n = 10 per group). All +3 and +2 subjects but only three +1 subjects had a clinical history of contact allergy to Ni(2+). Cytokine production of PBMC stimulated with Ni(2+) was determined by enzyme-linked immunospot and/or enzyme-linked immunosorbent assay. Ni2+ elicited significant production of all cytokines in PBMC from patch-test-positive subjects versus controls with a positive correlation between each cytokine and the patch test reactivity as well as with other cytokines. More subjects responded to Ni2+ above cut-off values with Th2-type cytokines as compared with IFN-gamma or IL-10; 100% of +3, 80% of +2, 50% of +1 and 0% of control subjects displayed reactivity to Ni2+ based on IL-4 and IL-13 assays. Despite the prevailing view of Ni2+ allergy as a type-1-mediated condition, the in vivo reactivity to Ni2+ correlated with a mixed Th1-type, Th2-type and regulatory cytokine response to Ni2+in vitro. The results accentuate the importance of type 2 responses in contact allergy and also demonstrate that IL-4 and IL-13 are reliable markers for Ni2+ allergy.

Improved detection of allergen-specific T-cell responses in allergic contact dermatitis through the addition of 'cytokine cocktails'

The gold standard for the diagnosis of allergic hypersensitivity is skin patch testing with the suspected allergens. This diagnostic tool, however, has distinct disadvantages, and therefore the development of alternative or complementary in vitro tests is of great importance. In this study, we evaluate the applicability of an in vitro test method, as developed earlier for nickel allergy, to detect allergen-specific T cells in the blood of patients allergic to frequent sensitizers (chromate, cobalt, paraphenylenediamine, fragrances and chloromethyl-isothiazolinone). Peripheral blood mononuclear cells (PBMCs) of allergic patients and healthy controls were cultured in the absence or presence of allergen. Additionally, type 1 (IL-7 and IL-12) or type 2 (IL-7 and IL-4) stimulating cytokines were added; after 6-day proliferation, IFN-gamma and IL-5 secretions were determined. Without the addition of cytokines, consistent allergen-induced proliferation was observed in PBMCs of nickel-allergic patients only. By contrast, the addition of type 1 or type 2 stimulating cytokines resulted in a significantly enhanced allergen-specific proliferation for all allergens tested (sensitivity increased from 26 to 43% or 38%, respectively, P < 0.05). In these cultures, allergen-induced IFN-gamma and IL-5 secretion was also significantly increased, compared to healthy controls (P < 0.05, for IFN-gamma sensitivity 79%, specificity 93%; for IL-5 sensitivity 74%, specificity 81%). In conclusion, these results demonstrate an increased proliferative capacity and cytokine production by allergen-specific T cells from allergic patients, but not of healthy individuals upon stimulation with allergens in combination with type 1 or 2 skewing cytokines. The present data warrant further exploration of the application of this test to a broader set of allergens.

T-cell function after interleukin-2 therapy in HIV-infected patients is correlated with serum cortisol concentrations

OBJECTIVES

To examine the effects of interleukin (IL)-2 therapy on in-vitro lymphocyte responsiveness in HIV-infected patients and to correlate these data with serum cortisol concentrations.

DESIGN

German prospective study.

METHODS

In adult patients (n = 32) treated with 9 x 10(6) IU/day interleukin-2, lymphocyte transformation tests (LTT), serum cortisol concentrations and CD4 T-cell counts were assessed before, during and after IL-2 therapy.

RESULTS

A significant decrease in responses towards mitogens and recall antigens (P < 0.05) was observed on day 7 after starting a 4- to 5-day IL-2 therapy as compared to baseline. Serum cortisol levels increased (P < 0.0001) reaching a maximum on day 4, and were still elevated on day 7 (P < 0.005). CD4 T-cell counts significantly decreased with a minimum on day 2 before increasing 2.4-fold above baseline on day 7 (P < 0.005 each). A positive correlation (P < 0.05 each) was observed for changes in cortisol levels and in LTT mitogen and antigen reactions (both day 7 - 0), changes in cortisol levels (day 3 - 0) and CD4 cell counts on day 2, and corticotrophin releasing hormone test results and LTT antigen reactions on day 7. LTT responses, cortisol levels and CD4 T-cell counts returned to baseline on day 30.

CONCLUSION

Serum cortisol concentrations are predictive of functional and numerical changes of T cells induced by IL-2 therapy.

[Tolerance induction towards nickel. From animal model to humans]

Nickel is the most common contact allergen in humans. Until recently, many questions concerning tolerance mechanisms to nickel were unresolved. Besides human ex vivo, intervention and observation studies, the establishment of a reproducible mouse model has contributed to the analysis of these mechanisms. A more detailed understanding of the pathogenesis of nickel allergy and tolerance towards nickel by investigations in an animal model and in human studies is a prerequisite for developing specific prevention and therapy of nickel allergy. With this article, we provide a review of the investigations concerning nickel allergy and give perspectives towards oral tolerance induction to nickel in the animal model and in humans.

Analysis of effector and regulatory immune reactivity to nickel

BACKGROUND

Diagnostic patch testing in allergic contact dermatitis faces the risk of boosting existing hypersensitivities or active sensitization. Risk-free and reliable in vitro assays using peripheral blood are, therefore, wanted.

OBJECTIVES

Here, we studied new approaches for in vitro monitoring of nickel-specific effector ad regulatory cell functions in allergic patients and potentially tolerized individuals.

METHODS

Lymphocyte proliferation assays were carried out with the allergen and additional IL-12/IL-7 or IL-4/IL-7 cytokine supplements. Release of IFN-gamma and IL-5 were assessed as measures for type-1 and type-2 effector T cell function, respectively, and IL-10 and TGF-beta1 to monitor possible regulatory T cell function reflecting immunological tolerance. After optimization of in vitro cut-off values, potency of these parameters was evaluated as compared with conventional nickel patch testing.

RESULTS

One hundred and fifty six outpatients were included in this study, 74 of whom presenting with a positive history of nickel allergy. Nickel-sulphate patch test results showed positive reactions in 43 patients, of whom 40 had a positive history (test sensitivity 54%; specificity 96%; overall accuracy 76%). Proliferation tests without cytokine supplementation showed an accuracy of 68%, which was further improved by supplementing IL-4/IL-7 (82%). IFN-gamma and IL-5 cytokine production, as revealed in IL-12/IL-7 and IL-4/IL-7 supplemented cultures, respectively, showed accuracies of 70% and 83%. As to the production of putatively immunoregulatory cytokines, IL-10 was most informative, with highest production rates in nickel-skin test negative individuals with long-lasting mucosal metal contact preceding skin piercing.

CONCLUSIONS

These results indicate that measuring both T cell proliferation and cytokine secretion profiles, in particular IL-5 release using IL-4/IL-7 supplemented medium, offers a promising improvement of the in vitro diagnostic options in monitoring nickel contact sensitization. Since oral nickel contact has been shown earlier to induce active tolerization, nickel-induced in vitro IL-10 production may help identify nickel-tolerized individuals.