Induction of the traits of the differentiated T-cell phenotype in the blast cells of patients with acute lymphoblastic leukemia. I. The expression of T-cell markers as affected by different inducers

The expression of T-lymphocyte markers has been demonstrated by blast cells of patients with non-T, non-B and pre-T-cell acute lymphoblastic leukaemia (ALL). The main inducing agent is phytohemagglutinin (PHA). Its action was enhanced when combined with phorbol ether (TPA) or ouabain. Dimethylsulfoxide, ouabain and concanavalin A had no similar inducing effect. TPA caused the expression of some T-cell markers revealed by monoclonal antibodies but had only a little inducing effect to E-receptor.     

Assessment of the action of taktivin on different stages of T-lymphocyte maturation

Tactivin, the thymic hormone preparation, evokes some phenotype alterations in T-cell precursors (elimination of SC-1 antigen and expression of Thy-1-antigen) and cortical thymocytes (a decrease in the number of thymocytes carrying PNA-receptor) similar to those arising in T-cell differentiation. Tactivin induces PNA+ -thymocyte response to PHA action and increases PHA response to PNA- -thymocytes. It is weakly mitogenic for T-cell precursors and PNA- -thymocytes. The data suggest that Tactivin may be used for the treatment of immune deficiencies with T-cell differentiation and function defects.     

Differences in electrophoretic mobility and cytochemistry of leukemic T-cells with identical immunologic phenotype (CD1 positive)

Leukaemic cells of acute T-lymphoblastic leukaemia and T-lymphoblastic lymphoma with secondary leukaemic course of disease which showed the same immunological phenotype (cortical thymocytes, thymocyte stage II), could be further differentiated according to their cytochemical pattern and electrophoretic mobility (EPM). Leukaemic cells of T-ALL usually reveal a high EPM, whereas EPM of leukaemic cells of T-lymphoblastic lymphoma was significantly lowered. In cytochemical respect acid phosphatase was positive in both cases of leukaemia. An activity of acid esterase, however, could only be demonstrated in leukaemic cells of T-lymphoblastic lymphoma. The findings are interpreted as manifestation of a different stage of maturity of both T-cell clones with the same immunological phenotype.     

Phytohemagglutinin-lnduced acquisition of T-cell surface markers by rat bone marrow precursor cells in the absence of the thymic microenvironment

Two monoclonal antibodies specific for different rat T-cell subpopulations, the anti-helper-T-cell antibody, W3/25, and the OX8 suppressor cell antibody were used to investigate lectin-stimulated T-lymphocyte differentiation of F-344 rat bone marrow cells in culture. Cytofluorometric analysis of freshly isolated lymphocytes from thymus and spleen revealed that these tissues contained both W3/25? and OX8-positive populations but differed with respect to the number of cells and receptor density distribution. By contrast, bone marrow-derived lymphocytes exhibited negligible W3/25? or OX8-associated fluorescence. However, several days after stimulation of bone marrow lymphocytes with phytohemagglutinin (PHA), cells appeared bearing these markers. Two-parameter histogram analysis of light scatter measurements with cell surface immunoflu-orescence indicated that this phenomenon represented the appearance of a new population of cells, presumably mature T cells, bearing an increased density of marker. These findings suggest an induction of differentiation of bone marrow T precursor cells by nonthymic factors (PHA) since lymphocytes lacking mature T-cell marker expression developed this characteristic after several days in culture.     

Adjuvant actions of polyclonal lymphocyte activators. II. Comparison and characterization of their actions in initiation and potentiation of immune responses to T-dependent and T-independent soluble antigens

Various polyclonal lymphocyte activators (PLA) such as capsular polysaccharide of Klebsiella pneumoniae (CPS-K), lipopolysaccharide of Escherichia coli (LPS), dextran sulfate (DS), concanavalin A (Con A), phytohemagglutinin (PHA), pokeweed mitogen (PWM), and polyadenylic-polycytidylic acid (poly A:U) were compared in their effects on antibody response to T-dependent antigen (bovine gamma globulin (BGG) and dinitrophenylated (DNP)-BGG) and T-independent antigen (DNP-Ficoll) and on induction of tolerance to T-dependent antigen. All of these PLA acted more or less to trigger the initiation of the antibody-forming mechanism for deaggregated BGG (DBGG) or DNP-BGG through their actions on the carrier-specific T-cell function. All of these PLA tested also acted more or less to inhibit the induction of the carrier-specific T-cell tolerance to DBGG. Moreover, some of these PLA could act to augment antibody response to DNP-Ficoll. The adjuvant action of PLA in the response to DNP-Ficoll worked as well in athymic nu/nu mice as in nu/+ mice, whereas that in the response to DNP-BGG did not occur in athymic nu/nu mice. The order of the strength of the action of PLA to trigger the initiation of the whole immune response to DBGG, that to trigger the carrier-specific T-cell function to DNP-BGG, and that to inhibit the induction of the whole tolerance to DBGG was very similar to each other: i.e., CPS-K ? Con A > LPS, DS, poly A:U, PWM and PHA. By contrast, the order of the strength of the action to inhibit the induction of T-cell tolerance to DBGG was ≧ = LPS > Con A, PWM and poly A:U > DS and PHA, and that of the action to augment the antibody response to DNP-Ficoll was CPS-K > LPS > Con A. CPS-K was the most potent in all of these immunological activities. It was concluded that PLA act generally to stimulate the immune response at its initiation step in which T cells in the case of T-dependent antigen and B cells in the case of T-independent antigen play a predominant role, but that individual PLA share this adjuvant activity in different fashions.     

Effects of changes in membrane potential on the cyclosporin-induced inhibition of T-cell proliferation.

Cyclosporin A (CsA) exerts its major immunosuppressive effect by inhibition of T-lymphocyte proliferation. The precise mechanism and target of its action has not yet been completely identified. CsA is also known to induce a rapid membrane depolarization in T lymphocytes. We have tested the role of CsA-dependent depolarization in the inhibition of T-cell proliferation by the drug. In these studies, induced membrane depolarization (in the presence of gramicidin or by replacing the Na+ content of the medium with K+) or hyperpolarization (in the presence of valinomycin) had no influence on the induction of T-cell competence by phorbol dibutyrate/ionomycin or by submitogenic concentrations of PHA, a target for CsA immunosuppression. However, regardless of the state of membrane potential during the induction of T-cell competence, the inhibition by CsA was the same as seen in normally polarized cells. We conclude that the depolarization induced by CsA is not a critical element in its inhibitory effect on T-cell proliferation.     

Folate requirement for blast cell transformation in mixed leukocyte cultures.

Mixed leukocyte cultures from normal donors were set up in standard tissue culture media. Blast cell transformation was measured 6 days later by ³H-thymidine uptake and assessed qualitatively with stained smears. Media RPMI 1629 and RPMI 1640 allowed much more intense blastogenesis than Medium 199, the difference being due to the low folic acid content of Medium 199 (0.01 mg/liter) compared with RPMI 1629 (10 mg/liter) and RPMI 1640 (1 mg/liter). Further experiments indicated that folic acid increased the multiplication rate of blast cells but did not promote the induction or initial transformation phases of the mixed leukocyte reaction. The effect of folic acid on the PHA response was entirely different: ³H-thymidine uptake in 3 day PHA cultures was decreased, and there was no apparent effect on the number or percentage of blast cells seen on the smears. The reason for this difference is at present unknown, but some possibilities are discussed.     

Late effects of the Chernobyl radiation accident on T cell-mediated immunity in cleanup workers

The main goal of this investigation was to evaluate the abnormal T-cell immunity in cleanup workers who took part in the cleanup after the Chernobyl accident in 1986. Peripheral blood mononuclear cells (MNCs) of apparently healthy cleanup workers (n = 134) were used to analyze the phenotype and proliferative response to mitogens in vitro. Evaluation of the MNC phenotype of cleanup workers did not reveal a significant disturbance in the T-cell subpopulation content except for an increase in CD3+CD16+56+ (NKT) cells. Immunophenotyping of phytohemagglutinin (PHA)-activated MNCs demonstrated suppression of CD4+ T-cell propagation and augmentation of CD8+ T-cell propagation in vitro compared to control individuals. DNA synthesis in the MNCs of cleanup workers was markedly inhibited after activation for 3 days with suboptimal concentrations of PHA, pokeweed mitogen and PMA. In contrast to control individuals, the monocytes of cleanup workers were able to stimulate the proliferation of T cells from healthy individuals but inhibited the proliferation of T cells from cleanup workers. This study affords a better understanding of the response of MNCs to stimulation with suboptimal concentrations of PHA and provides an approach to a more accurate analysis of the immunological disorders found after exposure to radiation from Chernobyl-related activities.     

Effect of T- and B-lymphocyte mitogens on interactions between lymphocytes and macrophages.

The mitogenic response of murine T cells ² to Con A, S-Con A and PHA was found to be macrophage-dependent. Optimal mitogenic responses were obtained when macrophage-depleted T-cell populations were reconstituted with 5% normal peritoneal macro-phages. Studies were carried out to investigate the effect of T- and B-cell mitogens on in vitro physical interactions between murine lymphocytes and macrophages. This was done by determining the number of T- or B cells binding to macrophages in the absence and in the presence of T- and B cell mitogens, and comparing the results of these experiments with the induction of lymphocyte proliferation. Con A increased the binding of T cells to macrophages when used in mitogenic doses (1–5 μg/ml). Dose response experiments showed that the same dose of Con A which produced maximal mitogenic stimulation also induced the greatest number of T cells to bind to macrophages. Nonmitogenic doses of Con A (20–50 μg/ml) did not enhance the binding of T cells, while identical doses of S-Con A both induced T cell mitogenesis and increased the number of T cells bound to macrophages. Similar results were obtained with PHA. None of the B-cell mitogens tested (LPS, EPO 127 and LAgl) increased the binding of either T or B cells to macrophages. PWM, which is mitogenic for both T and B cells, increased the binding of T cells to macrophages, but not that of B cells. In brief, the four T-cell mitogens tested (Con A, S-Con A, PHA, and PWM) induced specific physical interactions between T cells and macrophages, while none of the B-cell mitogens had any effect on the physical interactions between either B or T cells and macrophages when used in mitogenic doses.     

Changes in the organization and biosynthesis of cell surface acidic sugars during the phytohemagglutinin-induced blast formation of human T-lymphocytes

Use of cell electrophoresis combined with specific enzymes and varying ionic strength revealed a topological change of acidic sugars in lymphocyte membrane treated with a T-cell mitogen, phytohemagglutinin (PHA). The suggested alterations were an early translocation of hyaluronic acid to the cell periphery within 15 min of PHA addition and, 4 h later, the appearance of chondroitin sulphate in T-lymphocytes, but not in B-lymphocytes. As the contribution of chondroitin sulfate to the electrophoretic mobility increased with time up to 24 h, that of sialic acid decreased conversely. Several agents which block blast formation (2 mM ethylene glycol bis-β-aminoethylethyl-N,N,N′,N′-tetraacetic acid, 2 × 10⁻⁷ M ouabain, 0.1 μg/ml colchicine and 1 μg/ml cytochalasin B) also blocked the translocation of hyaluronic acid at the same concentrations. Chemical analysis of [¹⁴C]glycosaminoglycans by means of gel filtration followed by paper chromatography revealed a four-fold enhancement of the biosynthesis of chondroitin sulfate C after PHA stimulation. The presence of chondroitin sulfate in the cell periphery was also detected electrophoretically in T-cell type leukemia cells (MOLT-4B). These results suggest that the reorganization of glycosaminoglycans may be one of the membrane changes associated with blast formation of lymphocytes.     

Differential effects of concanavalin A and phytohemagglutinin on murine immunity. Suppression and enhancement of cell-mediated immunity.

To assess the effects of the selective T-cell mitogens concanavalin A (Con A) and phytohemagglutinin P (PHA) on cell-mediated immunity (CMI), the mitogens were injected before, with, or after intravenous (iv) challenge of mice with Listeria monocytogenes. Mitogenic treatment differentially influenced the CMI response to Listeria. Con A enhanced listericidal activity when given before or with Listeria challenge, but Con A suppressed the CMI response when given after infection with Listeria. In contrast, PHA enhanced listericidal activity at all intervals. Since Con A, but not PHA, affected the growth of Listeria in the spleens of mice 24 and 48 hr after infection, Con A was shown to have an immediate effect on the development of listericidal activity and PHA was shown to have a delayed effect. In addition, Con A induction of immediate nonspecific listericidal activity was short-lived, while PHA induced a longer-lasting effect on resistance to Listeria. The mitogen-induced effects in the CMI response to Listeria were shown to be dependent upon the activities of activated T cells. The enhancement and suppression of listericidal activity appears to result from the activation of different T-cell subpopulations, known to be stimulated preferentially by Con A or PHA.     

Further characterization of mitogen-induced autorosette-forming cells: correlation with T-cell subsets and with lymphocyte proliferative responses to mitogens

Spontaneous autologous rosette-forming cells (ARFC), which form rosettes with autologous erythrocytes, have been of interest as a subset of thymus-derived lymphocytes (T cells). An association of these cells with concanavalin A (Con A)-induced ARFC has been suggested. Furthermore, the Con A-induced ARFC have been shown to be a suppressor T-cell subset in the Con A-generated suppressor system. We have previously reported the induction of ARFC from T cells by several T-cell mitogens such as phytohemagglutinin-P (PHA) and allogeneic non-T cells other than Con A. In the present report, we further characterized the mitogen-induced ARFC and have extended the study to patients with systemic lupus erythematosus (SLE). We have found that ARFC are also inducible from peripheral blood T cells by pokeweed mitogen (PWM). Studies of T-cell surface markers on the ARFC using OKT monoclonal antibodies confirmed the induction of ARFC from both OKT4- and OKT8-reactive T cells by either Con A, PHA, or PWM stimulation. However, OKT4-reactive T cells were the major cellular source of the ARFC induced by all of the mitogens. In studies of SLE patients, proportions of both Con A- and PWM-induced ARFC were found to be significantly low in PBL of SLE patients treated with moderate or large doses of prednisone, with or without concomitant immunosuppressants, but not in SLE patients without such treatment. Proportional analysis of the T cells and their subsets suggested association of these alterations in the mitogen-induced ARFC with the OKT4-reactive T cells, since a significant decrease in the OKT4-reactive T-cell subset was demonstrated in the PBL of these patients. Proportions of PHA-induced ARFC, however, were not significantly different between SLE patients and healthy adults. Moreover, positive correlations of the mitogen-induced ARFC with lymphocyte proliferative responses to each mitogen were established in both SLE patients and healthy adults. These results further support our previous observation that suggest the receptors for autologous erythrocytes are enhanced or reexpressed on those T cells which are highly activated by mitogens.     

Immune function in aged mice. I. T-cell responsiveness using phytohaemagglutinin as a functional probe.

The loss of cell-mediated immunity with age was assessed by a detailed analysis of the in vitro response of murine lymphocytes to the well-defined probe of T-cell function, PHA (phytohaemagglutinin). The reduced mitogenic activity of lymphoid cells from old mice compared with young mice could not be explained in terms of a shift in kinetics of the responding cells. Removal of macrophages, which are known to exert a regulatory effect on T-cell function, failed to reverse the poor response of old lymphoid cells. Furthermore, no evidence was found for a role of soluble inhibitors released by either lymphocytes or macrophages in the decreased response of old cells. Not only were old cells less efficient in producing such factors, but in addition, they responded less well to them than did young cells. Taken together, these observations implied that the defect in PHA responsiveness of old cells is due to a disturbance in the T cells themselves rather than to any extracellular influences. The total number of T cells, assessed by labelling with anti-Thy-1 serum was comparable in old and young animals. Selective depletion of a subpopulation of PHA-reactive cells was excluded by direct quantitation of PHA-binding cells. Thus, 25% of small lymphocytes from the spleens of old mice bound ¹²⁵I-labelled PHA ([¹²⁵I]PHA) compared with 15% in the case of young mice. To show that the cells binding PHA were those reacting to it, a suicide technique was used. Spleen cells pretreated with [¹²⁵I]PHA failed to respond to subsequent challenge with the specific mitogen, but could mount a normal response to a control (B-cell), mitogen, LPS (lipopolysaccharide). When PHA cultures were carried out in the presence of colchicine, fewer cells from old mice were found to react to the mitogenic signal. In the absence of evidence for depletion of precursor cells, the conclusion was reached that the T-cell defect in old mice is more likely to be qualitative than quantitative, perhaps due to metabolic or structural abnormalities preventing lymphocyte transformation and/or proliferation.     

Dendritic cell populations in colon and mesenteric lymph nodes of patients with Crohn's disease.

Dendritic cells (DCs) are key cells in innate and adaptive immune responses that determine the pathophysiology of Crohn's disease. Intestinal DCs migrate from the mucosa into mesenteric lymph nodes (MLNs). A number of different markers are described to define the DC populations. In this study we have identified the phenotype and localization of intestinal and MLN DCs in patients with Crohn's disease and non-IBD patients based on these markers. We used immunohistochemistry to demonstrate that all markers (S-100, CD83, DC-SIGN, BDCA1-4, and CD1a) showed a different staining pattern varying from localization in T-cell areas of lymph follicles around blood vessels or single cells in the lamina propria and in the MLN in the medullary cords and in the subcapsular sinuses around blood vessels and in the T-cell areas. In conclusion, all different DC markers give variable staining patterns so there is no marker for the DC.     

History of immunology. Development of the concept of immunologic specificity, I

The induction of differentiation in human malignant T-lymphoblastic cell lines MOLT-3 and Jurkat by the tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA) was examined using the monoclonal antibodies OKT3, OKT4, OKT6, and OKT8 which are known to react with human T-cell differentiation antigens. It was found that in the presence of nanomolar concentrations of TPA the proportion of OKT3⁺ (mature T-cell marker) cells increased while the proportion of OKT4⁺, OKT6⁺, and OKT8⁺ (relatively immature T-cell markers) cells decreased. These changes in the distribution of the OKT antigens in MOLT-3 cells were found to be more prominent with MOLT-3 cells than when the Jurkat cells were used. In studies using a double labeling approach it was found that although the OKT3⁺ and E-rosette-positive (E⁺) cells appeared to belong to the same subpopulations of MOLT-3 cells, the OKT3 antigen was probably not related to the receptor for sheep erythrocytes because adsorption of the OKT3 antibody did not block E-rosette formation. Studies using the DNA synthesis inhibitor, arabinosylcytidine (ara-C) also indicate that DNA synthesis was not required for the induction of more mature T-cell antigens in the malignant T-cell lines by TPA. These studies, taken together with our earlier reports, support the conclusion that namomolar concentrations of TPA can induce differentiation in these malignant T-cell lines. Furthermore we have shown that the T-cell hybridoma antibodies are useful markers to detect differentiation changes in human T cells.     

Cytomegalovirus infection in Gambian infants leads to profound CD8 T-cell differentiation

Cytomegalovirus (CMV) infection is endemic in Gambian infants, with 62% infected by 3 months and 85% by 12 months of age. We studied the CD8 T-cell responses of infants to CMV following primary infection. CMV-specific CD8 T cells, identified with tetramers, showed a fully differentiated phenotype (CD28(-) CD62L(-) CD95(+) perforin(+) granzyme A(+) Bcl-2(low)). Strikingly, the overall CD8 T-cell population developed a similar phenotype following CMV infection, which persisted for at least 12 months. In contrast, primary infection was accompanied by up-regulation of markers of activation (CD45R0 and HLA-D) on both CMV-specific cells and the overall CD8 T-cell population and division (Ki-67) of specific cells, but neither pattern persisted. At 12 months of age, the CD8 T-cell population of CMV-infected infants was more differentiated than that of uninfected infants. Although the subpopulation of CMV-specific cells remained constant, the CMV peptide-specific gamma interferon response was lower in younger infants and increased with age. As the CD8 T-cell phenotype induced by CMV is indicative of immune dysfunction in the elderly, the existence of a similar phenotype in large numbers of Gambian infants raises the question of whether CMV induces a similarly deleterious effect.     

Proliferative response of normal and activated human lymphocytes to tetradecanoyl phorbol acetate

The mitogenicity of 12-O-tetradecanoyl phorbol-13-acetate (TPA) for normal human peripheral blood mononuclear cells was investigated. TPA was a weak mitogen giving simulation indices in the range 2.5 to 10.5 at the optimum concentration (10 ng/ml) compared with 39 to 95 for phytohemagglutinin (PHA) at its optimum concentration (1 μg/ml). No absolute requirement for a comitogen could be demonstrated, however TPA and PHA were synergistic in their action at low concentrations, and additive at optimum concentrations. Cell fractionation by rosetting with sheep erythrocytes showed that most of the proliferative response to TPA occurred in the T-cell fraction, however some proliferation of non-T cells was also observed. Surface marker studies showed that this could not have been due to residual T cells in the non-T fraction. A small number of monocytes was required for optimal proliferation of T cells in response to TPA. After a 3-day incubation with mitogen, the responding cell populations were tested for binding of a range of antibodies specific for T-cell (OKT3, OKT4, OKT8, and OKT11), “natural killer” (NK) cell (anti-Leu-7), monocyte (FMC17), and B-cell (anti-human immunoglobulin) surface markers. These experiments indicated that the responding cell types were T cells and B cells, but not NK cells or monocytes. Marked modulation of the antigen detected by OKT4, and to a lesser extent that detected by OKT3, in the presence of TPA precluded determination of which subpopulations of T cells proliferated in response to TPA. TPA was also tested for its ability to “maintain” activated T-cell blasts in a standard assay for interleukin 2 (IL-2). Mitogen-activated T cells were strongly responsive to TPA in this assay, but progressively lost responsiveness when maintained in crude IL-2 for about 2 weeks. Thus TPA does not have “maintenance” (i.e., IL-2-like) activity. However, small amounts of TPA acted synergistically with PHA in maintaining blast populations which were not responsive to TPA alone. This illustrates the importance of using long term IL-2-dependent cell lines for quantitation of IL-2 in supernatants prepared by stimulating T cells with these agents.     

The non-genomic effects on Na+/H+-exchange 1 by progesterone and 20alpha-hydroxyprogesterone in human T cells

Progesterone is an endogenous immunomodulator and can suppress T-cell activation during pregnancy. We have previously shown that the non-genomic effects of progesterone, especially acidification, are exerted via plasma membrane sites and suppress cellular genomic responses to mitogens. This study aimed to show that acidification is due to a non-genomic inhibition of Na(+)/H(+)-exchange 1 (NHE1) by progesterone and correlate this with immunosuppressive phytohemagglutinin (PHA)-induced T-cell proliferation. The presence of amiloride-sensitive NHE 1 was identified in T cells. The activity of NHE1 was inhibited by progesterone but not by 20alpha-hydroxyprogesterone (20alpha-OHP). Furthermore, 20alpha-OHP was able to compete with progesterone and release the inhibitory effect on the NHE1. The inhibition of NHE1 activity by progesterone-BSA demonstrated non-genomic action via plasma membrane sites. Finally, co-stimulation with PHA and progesterone or amiloride, (5-(N, N-dimethyl)-amiloride, DMA), inhibited PHA-induced T-cell proliferation, but this inhibition did not occur with 20alpha-OHP and PHA co-stimulation. However, when DMA was applied 72 h after PHA stimulation, it was able to suppress PHA-induced T-cell proliferation. This is the first study to show that progesterone causes a rapid non-genomic inhibition of plasma membrane NHE1 activity in T cells within minutes which is released by 20alpha-OHP. The inhibition of NHE1 leads to immunosuppressive T-cell proliferation and suggests that progesterone might exert a major rapid non-genomic suppressive effect on NHE1 activity at the maternal-fetal interface in vivo and that 20alpha-OHP may possibly be able to quickly release the suppression when T cells circulated away from the interface.     

T-cell activation without proliferation in juvenile idiopathic arthritis

A study was done to determine if the differentiation and activation phenotype of T cells in synovial fluid (SF) from patients with juvenile idiopathic arthritis (JIA) is associated with T-cell proliferation in situ. Mononuclear cells were isolated from 44 paired samples of peripheral blood and SF. Differentiation and activation markers were determined on CD4 and CD8 T cells by flow cytometry. Cell-cycle analysis was performed by propidium iodide staining, and surface-marker expression was also assessed after culture of the T cells under conditions similar to those found in the synovial compartment. The majority of the T cells in the SF were CD45RO+CD45RBdull. There was greater expression of the activation markers CD69, HLA-DR, CD25 and CD71 on T cells from SF than on those from peripheral blood. Actively dividing cells accounted for less than 1% of the total T-cell population in SF. The presence or absence of IL-16 in T-cell cultures with SF or in a hypoxic environment did not affect the expression of markers of T-cell activation. T cells from the SF of patients with JIA were highly differentiated and expressed early and late markers of activation with little evidence of in situ proliferation. This observation refines and extends previous reports of the SF T-cell phenotype in JIA and may have important implications for our understanding of chronic inflammation.