Esquistossomose humana: participação de células da linhagem monocítica/macrofágica e de citocinas na imunorregulação da resposta aos antigenos do Schistosoma mansoni

Abstract

Schistosoma mansoni eggs deposited in host tissues induce the appearance of a granulomatous- type hypersensitivity reaction, which is mainly responsible for the immunopathology observed in this disease. The cells of the monocytic/macrophage lineage represent an important cell population participating in these granulomatous reactions, both by the number and variety of soluble factors produced. In this work, we evaluated the process of multinucleated giant cell formation on immunoregulation of the response to S. mansoni antigens during cell proliferation and granuloma formation in vitro assays by mononuclear cells from individuals with chronic intestinal schistosomiasis. We evaluated the main cytokines (IL-4, IL-5, IL-10, IL-13, IFN and TNF) produced during these assays by the ELISA technique, the expression of surface markers (CD 29, CD 54 and HLA-DR) during the formation of multinucleated giant cells by flow cytometry, and the consequences of the response of mononuclear cells obtained from individuals with chronic intestinal schistosomiasis to S. mansoni antigens on functional aspects of monocytes and macrophages, such as metabolic activity evaluated by MTT metabolization and the production of the monokine TNF- by ELISA. The results obtained showed that multinucleated giant cells, once formed, are involved in immunoregulatory mechanisms of proliferative responses and also associated with a concomitant decrease in the intensity of granulomatous reactions developed in vitro. In addition, we found a probable mechanism responsible for this immunoregulation would be the modulation of HLA-DR, CD29 and CD54 expression. The data obtained by stimulation with S. mansoni antigens showed the existence of an unrestricted (Th0) and very complex pattern of cytokine production in human schistosomiasis, both by the types of cytokines secreted and by the sequence in which they are produced. The results of this work suggest that the pattern of cytokine production by mononuclear cells after antigenic stimulation and the local development of multinucleated giant cells may be probable causes of immunoregulation of the response observed in human schistosomiasis.