Expression of CD163 on human histiocytic cells is different in tuberculosis-induced and schistosomiasis-induced granulomas

摘要

Sir. Granulomatous inflammation can be characterized by the predominant type of participating T-cell help, either type 1 T-cell help (Th1) or Th2 predominance. In Th1-mediated granulomas, cytokines with potent pro-inflammatory activity, such as interferon (IFN)-gamma, interleukin (IL)-12, and tumour necrosis factor-alpha, are abundant. In Th2-mediated granulomas, the predominant cytokines, IL-4, IL-5, IL-10, and IL-13, have variable levels of immune-modulating activity. Established mouse models exist for both Thl-mediated and Th2-mediated granulomas. Thl-mediated granulomas in the lungs are induced by pulmonary embolization with Mycobacterium tuberculosis antigen-coated pellets, and Th2-mediated granulomas by pulmonary embolization with Schistosoma mansoni antigen-coated pellets. CD163, a member of the scavenger receptor cysteine-rich family, is expressed only on cells of the monocytic lineage. Recently, CD163 has been suggested to be a pattern recognition receptor and a critical part of innate immunity. Expression of CD163 can be up-regulated by anti-inflammatory stimuli such as glucocorticoids and IL-10, and upon stimulation of Toll-like receptors. Proinflammatory IFN-gamma of Thl T cells leads to down-regulation of CD163 expression.6 There is also evidence for down-regulation by Th2 IL-4 and IL-13.5 In Thl-mediated granulomas, as IFN-y and IL-12 are the predominant cytokines, low levels of CD163 expression would be expected. In Th2-mediated granulomas, which are characterized by cytokines such as IL-4 and IL-10, expression depends on whether the inhibitory effects of IL-4 or the activating effects of IL-10 are predominant. We would expect CD163 expression to be more pronounced than in Thl-mediated granulomas. In foreign body (FB) reactions, which are classically seen to be independent of T-cell help, the level of CD163 expression is not predictable. In the present study, we characterized patterns of CD163 expression by the monocytic lineage in archetypical Th1-induced, Th2-induced and non-immunological FB-induced granulomas.