Multicentric reticulohistiocytosis associated arthritis responding to anti-TNF and methotrexate.

We present a patient with therapy resistant multicentric reticulohistiocytosis (MRH). MRH is a rare granulomatous, multisystem disease characterised most frequently by disfiguring papulonodular skin lesions and sometimes a destructive polyarthritis, though any organ can be involved. Abnormal histiocytic reactions to an undetermined stimulus (possibly an associated mycobacterial infection, auto immune process or neoplastic process) have been proposed as an underlying mechanism. The diagnosis is confirmed by histopathology of the cutaneous nodules and/or synovial membrane by the presence of CD68-positive histiocytes and multinucleated giant cells with an eosinophilic 'ground-glass' cytoplasm. Recent studies have identified TNFalpha and other inflammatory cytokines to be highly expressed in the synovium and synovial fluid of affected joints in patients with MRH. Based on these findings, we treated our patient with infliximab in combination with methotrexate with marked improvement of morning stiffness, tender and swollen joint count, visual analogue scale and health assessment questionnaire after his third infusion. However, the nodules did not markedly resolve. When treating patients with MRH with TNFa neutralizing drugs, one has to keep the possible association with malignancy in 15-30% of cases in mind and these products should be used with caution.

T cell signal transducer and activator of transcription (STAT) 4 and 6 are affected by adalimumab therapy in rheumatoid arthritis.

OBJECTIVES: TNF-alpha inhibition therapy affects the systemic immune response in rheumatoid arthritis by influencing T cell subtypes (Th1, Th2, Treg), but its effect on the intracellular signal transduction in T cells remains largely unexplored. Here we studied the activation of Th1-associated signalling molecule STAT4 and Th2-associated STAT6 in CD4+ T cells. METHODS: Eight rheumatoid arthritis patients were studied before and after 12 weeks of adalimumab therapy and compared to 8 healthy individuals. Peripheral blood mononuclear cells (PBMC) were analysed flow cytometrically either directly after isolation or after 24 hours of anti-CD3/anti-CD28 stimulation, to determine spontaneous and IL-4/IL-12-induced STAT4 and STAT6 phosphorylation in CD4+ T cells. Cytokine production by stimulated PBMC was measured in the supernatant using a cytometric bead array. Non-parametric statistical tests were applied. RESULTS: After adalimumab therapy, phospho-STAT6 increased, both in freshly isolated and anti-CD3/anti-CD28-stimulated CD4+ T cells. The STAT6 response to brief IL-4 stimulation did not change. In healthy individuals and adalimumab-treated patients, anti-CD3/anti-CD28 induced the phosphorylation of STAT4, but not in untreated patients. IFN-gamma production in untreated patients was significantly lower than in healthy individuals or adalimumab-treated patients. In contrast, the production of IL-4, IL-6 and IL-12 was not influenced. CONCLUSIONS: Adalimumab therapy increases Th2-associated STAT6 phosphorylation and restores the activation-induced STAT4 phosphorylation to the levels in healthy individuals. This advocates against a pro-inflammatory effect of Th1-associated STAT4 and might provide an explanation for the influence of TNF inhibition therapy on the systemic T cell response in rheumatoid arthritis.

Basophil activation test by flow cytometry: present and future applications in allergology.

The diagnosis of allergic reactions in clinical practice rests upon both clinical history and the demonstration of specific immunoglobulin E (sIgE), either in the serum or via skin tests. However, for various reasons, identification of the offending allergen(s) is not always possible. Moreover, not all allergies are IgE-mediated. In an attempt to find reliable methods to investigate hypersensitivity reactions, histamine and sulfidoleukotriene release tests have long been introduced. However, relatively few comprehensive quality reports have been published so far. Upon challenge with a specific allergen, basophils not only secrete quantifiable bioactive mediators but also upregulate the expression of different markers which can be detected efficiently by flow cytometry using specific monoclonal antibodies. This review addresses the principals, particular technical aspects and pitfalls as well as the clinical and research applications of flow-assisted analysis of in vitro activated basophils.

Combined analysis of intracellular signalling and immunophenotype of human peripheral blood basophils by flow cytometry: a proof of concept.

BACKGROUND: The signal transduction pathways and control mechanisms involved in IgE-mediated basophil activation remain incompletely understood. OBJECTIVES: To investigate whether basophilic intracellular signal transduction and immunophenotype can be analysed simultaneously by flow cytometry. METHODS: Basophils in whole blood were stimulated with anti-IgE and latex antigen at various concentrations and during different time courses. Phosphorylation of p38 mitogen-activated protein kinase (MAPK) as a representative of the intracellular signal transduction pathway and surface expression of CD63 was assessed simultaneously flow cytometrically. The effect of pre-incubation with IL-3 was assessed. RESULTS: Stimulation of the basophils with anti-IgE and allergen induces a rapid phosphorylation of p38 MAPK that peaks between 1 and 5 min and returns to baseline levels after 60 min. In contrast, CD63 up-regulation demonstrates a maximal but more continuous expression that peaks approximately 5 min later than phosphorylation of p38 MAPK. Specific inhibition of p38 MAPK reduced or almost completely abrogated up-regulation of CD63. Pre-incubation of the basophils with IL-3 produces a rapid p38 MAPK phosphorylation over basal levels, but this was weaker and shorter than for anti-IgE stimulation. Pre-incubation of the basophils with IL-3 did not potentiate anti-IgE-induced phosphorylation of p38 MAPK and did affect spontaneous or IgE-mediated CD63 up-regulation. CONCLUSIONS: This study provides the proof that the flow cytometer allows an integrated analysis of basophilic intracellular signalling and immunophenotyping. Owing to its technical simplicity, the low number of cells required and rapid analysis, the technique seems promising for use in the clinic as a diagnostic tool or to monitor therapy. CAPSULE SUMMARY: This study is the first to provide evidence for a combined analysis of basophilic intracellular signalling and immunophenotyping by flow cytometry. Owing to its technical simplicity, the low number of cells required and rapid analysis, the technique seems promising for use in the clinic as a diagnostic tool or to monitor therapy.

Influence of anti-tumor necrosis factor therapy (Adalimumab) on regulatory T cells and dendritic cells in rheumatoid arthritis.

OBJECTIVE: To investigate whether anti-TNF therapy could have an effect on dendritic cells (DCs) and regulatory T cells in rheumatoid arthritis (RA) patients. METHODS: A four-colour flow cytometric technique was used to measure CD4+CD25+ T cells i.e. CD4+CD25high+ (regulatory T cells) and CD4+CD25low+ (activated T cells)), DCs as well as the in vitro, intracellular, lipopolysaccharide-stimulated cytokine production of DCs. RESULTS: Clinical and laboratory parameters of disease activity decreased after anti-TNF treatment. Before anti-TNF therapy, RA patients demonstrated a decreased count of Th2-promoting lymphoid DCs as compared to controls and after anti-TNF therapy this decrease was sustained. Intracellular cytokine production was only found in the myeloid DCs population and there was a higher production of TNF-alpha and IL1-b as compared to healthy controls. Treatment did not alter this cytokine production. Before anti-TNF therapy, the percentage CD4+CD25+ T cells was significantly elevated in RA patients than in healthy controls. CONCLUSION: These results demonstrate anti-TNF to be a potent anti-inflammatory drug, as mirrored by the decrease in clinical and biological parameters as well as the decrease in activated CD4+ T cells. However, in this study no demonstrable effect on DCs and regulatory T cells was found.