Data concerning the presence of T-cell-derived cytokines in the rheumatic joint are conflicting, challenging the hypothesis that rheumatoid arthritis (RA) is a T-cell-mediated disease. In this study synovial tissue specimens of 11 patients with RA and eight patients with osteoarthritis (OA) were stained for interferon-gamma (IFN-gamma) and its receptor. The level of expression of IFN-gamma was compared with that in tissue specimens of delayed-type hypersensitivity (DTH) reactions of the skin and of chronic tonsillitis. Furthermore, the percentage of T-lymphocytes which stained positive for IFN-gamma was determined using double staining techniques. IFN-gamma and its receptor were detected in all patients with RA and in 7/8 and 3/8, respectively, of patients with OA. Expression of IFN-gamma (P<0.02) and IFN-gamma receptor (P<0.01) in synovial tissue of patients with RA was more abundant compared with that in patients with OA. Although IFN-gamma could be detected in RA synovial tissue, the level of expression was less when compared with DTH reactions of the skin and tonsillitis. The percentage of CD3+ cells being positive for IFN-gamma was approximately 1% in RA, whereas in DTH reactions of the skin it was >90% and in tonsillitis approximately 30%. We conclude that the presence of IFN-gamma and its receptor in RA synovial tissue suggests a role for this cytokine in the ongoing immunological reaction of the inflamed joint.

Local cytokine profiles in skin biopsies from allergic and irritant patch test reactions were determined by in vivo immunohistochemistry to differentiate between these 2 clinically identical afflictions especially at the time of final reading in diagnostic patch testing. Biopsies were taken from established allergic persons after specific allergic patch test.‐, to epoxy resin (1%) and formaldehyde (1%) and from non‐allergic individuals with irritant patch tests to sodium lauryl sulfate (10%) and formaldehyde (8%). At 72 h after application of the agents, significantly enhanced frequencies of dermal infiltrating cells, producing IL‐1α, TNF‐α. IL‐2. and IFN‐γ per 100 infiltrating cells in the dermis. were observed in allergic as well us irritant patch test reactions, as compared to normal skin. Significantly higher frequencies of IL‐ Iα‐producing cells were observed in biopsies from epoxy resin (1%) allergen‐affected and sodium lauryl sulfate (10%) irritant‐affected skin as compared to formaldehyde (1%) allergen‐affected skin. In addition, significantly higher frequencies of TNF ‐α reproducing cells were observed in epoxy resin allergen‐affected skin us compared to Formaldehyde (1%) allergen‐affected and formaldehyde (8%) irritant affected skin. The allergic and irritant patch test reactions showed similar levels of expression of the Thl cytokines IL‐2 and IFN‐γ in the dermis. confirmed by probe based detection of IL‐2 mRNA and IFN‐γ‐ mRNA, In conclusion, the described similarity shows that allergens and irritants can induce the same profile of IL‐la. TNF‐α. IL‐2. and IFN‐γ production, resulting in the near impossibility of discriminating between allergic and irritant contact dermal is at the lime of patch test reading.

The population of folliculo-stellate (FS) cells of the rat anterior pituitary has been shown to be ultrastructurally and immunohistochemically heterogeneous. Based on the overlap of ultrastructural characteristics, the localization in the anterior pituitary and the co-expression within the same cel of the S-100 protein (a marker for FS cells) and MHC-class II determinants (an immune marker) we concluded that a partial overlap exists between the population of FS cells and the monocyte-derived dendritic cells (DC). In this report we describe that interleukin-6 (IL-6) immunoreactivity was found in situ in stellate cells of the rat, mouse and human anterior pituitary at a very low density (< 1% of the cells); the topography was reminiscent of the distribution of FS cells. In the present study we also analyse three different pituitary cell separation methods, in order to study the functional heterogeneity of the FS cells in vitro, and to verify whether functionally distinct subpopulations exist within the FS cell group. Production of bioactive IL-6 was measured in conditioned media of rat anterior pituitary cells separated by (i) bovine serum albumin (BSA) gradient sedimentation at 1 g, (ii) Nycodenz gradient and (iii) a magnetic cell separation (MACS) technique. Production of bioactive IL-6 by cell cultures of 1 to 4 days was correlated with the proportional number of S100 immunoreactive and S100 producing cells, but was not correlated with the proportional number of MHC-class II expressing (OX6-positive) dendritic cells (DC). The distribution pattern of OX6-positive DC was found to partly overlap with the distribution pattern of S100-positive cells in the BSA gradient. Co-sedimentation of S100-positive FS cells and MHC-class II-expressing DC was not restricted to the top fractions of the BSA gradient, but was also found in the low density Nycodenz fraction. MACS separation of the rat anterior pituitary cells resulted into a population enriched in OX6 and OX62 positive DC and a population devoid of such cells, while S100+ cells were equally divided into these two subpopulations. Although there was a significantly decreased production of IL-6 as compared to that of an original pituitary cell population, both MACS separated populations were equal in IL-6 production. The diminution in IL-6 production in both populations may be the result of an impediment of paracrine communication due to the MACS separation into these two populations. Our data also show that a subpopulation of FS cells was capable of stimulating T cell proliferation in vitro. Concomitantly with the distribution pattern of S100- and OX6-immunoreactive cells in the BSA and Nycodenz gradient fractions, we found a similar pattern of stimulation of T cell proliferation. Unlike the IL-6 production pattern, the T cell stimulating capacity was present in the MHC-class II-enriched cell population but absent in the MHC-class II-depleted cell population. These findings-together with earlier in situ histochemical data-suggest that there is an OX6+ S100- subpopulati...

No abstract