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Cytokines are protein mediators that play a part in inflammation, the immune response, cell growth, repair, and fibrosis. All of these are continuing processes in active rheumatoid arthritis (RA), and so it would be expected that many cytokines would be actively produced in RA joints. Here, the molecular strategies devised to study the possible role of cytokines in the pathogenesis of RA, are reviewed and some of the initial results described. The relative abundance of various cytokines is 'catalogued' and then attention is turned to an attempt to discover which cytokines are of major importance in the pathogenesis. Neutralising antibodies to cytokines were used for that purpose, and it was found that tumour necrosis factor alpha (TNF alpha) is one of the major signals regulating the production of interleukin-1 in the RA, but not in the osteoarthritic joint. To understand further the dynamics of the cytokine network localisation of the cytokine producing cells by immunostaining--for example, TNF alpha, is currently being established.

Attempts to detect immune mediators in RA synovial fluids by bioassay or radioimmunoassay have yielded conflicting results, and so we have begun to analyse the complex immunological reactions occurring within the rheumatoid joint using recombinant DNA technology. High levels of Interleukin-2 (IL-2) and IL-2 receptor transcripts were found in the mononuclear cells of the rheumatoid lesions. Interferon gamma (IFN gamma) mRNA was also detected, although at lower level than IL-2. To investigate the possible relevance of IL-2 and IL-2 receptor mRNA expression to the chronicity of the disease, RA joint cells were cultured in the absence of any stimulus, and the duration of mRNA expression compared to that of blood mononuclear cells (PBM), optimally stimulated. IL-2 mRNA was found to persist in culture for many days, in contrast to its transient (less than 24 h) presence in stimulated PBM. IL-2 receptor expression was also prolonged. In contrast IFN gamma mRNA, present at biopsy in 10/12 RA samples, was found to increase significantly in vitro. These results suggest that persistent T cell activation is of importance in the pathogenesis of RA, and suggests that prolonged mediator production (IL-2 and IFN gamma) may be of importance. The elevation of IFN gamma mRNA in culture and its lower relative expression suggests that there are inhibitory immunoregulatory influences within the RA joint. To determine whether abnormal IL-2 mRNA expression may be due to a genetic defect in the region controlling IL-2 gene expression, Southern blotting analysis of genomic DNA was performed with a 5' flanking probe using normal, RA and systemic lupus erythematosis patients. No abnormalities were detected.

La composizione del colostro è sostanzialmente diversa da quella del latte non solo dal punto di vista nutrizionale ma anche da quello immunologico essendo provvisto oltre che di componenti necessarie per il fabbisogno e lo sviluppo del vitello, anche di diverse sostanze in grado sia di conferire al neonato una immunità di tipo passivo sia di modularne il sistema immunitario quali citochine, componenti antibatteriche come lattoferritina, lisozima, lattoperossidasi, immunoglobuline e polipeptidi ricchi in prolina. In questo studio sono stati utilizzati due differenti metodologie per valutare l’effetto immunomodulatore di 11 componenti del colostro bovino: una basata sulla quantificazione di IL 2 prodotta da linfociti ibridoma-derivati, l’altra basata sulla misurazione della proliferazione di linfociti ottenuti da topi. In entrambi i modelli sperimentali i linfociti erano di tipo DO11.10, transgenici per il recettore TCR in grado di riconoscere il peptide antigenico dell'ovoalbumina (OVA323-339) esposto sul recettore di tipo MHCII (I-Ad). I risultati ottenuti per 7 componenti colostrali hanno evidenziato una buona correlazione tra le due metodiche facendo ipotizzare la possibilità di impiegare le linee cellulari come alternativa all’impiego di animali come fonte di linfociti per la valutazione dell’attività immunomodulatoria delle componenti colostrali. La ricerca ha previsto anche la valutazione dell'effetto esercitato dagli stessi prodotti colostro-derivati sul fenotipo delle cellule presentanti l'antigene (APC) ed a tal fine sono state valutate le variazioni di alcuni marker di superficie (CD 40, CD 80, CD 86 e MHC II) coinvolti nella produzione citochinica. Inoltre è stata quantificata la produzione di diverse citochine presenti nel surnatante delle cellule T poste in coltura con diverse concentrazioni di prodotti colostro derivati. I risultati di questa seconda fase di studio hanno consentito di osservare come i prodotti colostrali testati siano in grado di modulare il profilo citochinico agendo sui marker di superficie con una polarizzazione della risposta immunitaria in senso anticorpale (Th2) o, in altri casi, verso una risposta cellulo-mediata (Th1).

Dendritic cells (DC) are important initiators of an immune response so understanding the factors controlling antigen acquisition and presentation has important consequences for the use of these cells in vaccines and other forms of immunotherapy. We investigated the factors that influence phagocytosis by immature bone marrow-derived DC (BMDC) and the effect of interleukin-10 (IL-10) on this process. Two sizes of fluorescent particles and recombinant bacillus Calmette-Guèrin expressing the green fluorescent protein (rBCG) were used as particulate antigens. The percentage of cells taking up the antigen was found to be dependent on the size and dose of the particles, and the length of exposure to them. BMDC exposed to IL-10 at various concentrations for different periods exhibited no distinguishable change in antigen uptake. However, if BMDC treated with IL-10 and rBCG were then exposed to a second dose of particulate antigen, uptake was increased compared with those BMDC not treated with IL-10. The expression of major histocompatibility complex class II, CD80, CD86 and CD11c by BMDC after phagocytosing rBCG or inert beads, was inhibited when the BMDC were pretreated with IL-10. In contrast, the expression of CD25 was increased. BMDC that had taken up BCG or purified protein derivative (PPD) were able to stimulate primed T-cell proliferation but this was severely inhibited if the BMDC were cultured with IL-10 before exposure to the antigen. This work suggests that although IL-10 does not affect the phagocytic capacity of BMDC, it does inhibit maturation of the cells and consequently, T-cell activation.