To increase our understanding of the mechanisms that play a role in host immune responses, we investigated the effects of C. parvum antigens on the phenotype of mouse and human dendritic cells (DCs). Cryptosporidium parvum antigens induced DC activation as indicated by upregulation of the maturation marker CD209, as well as by the production of the cytokines interleukin-12 p70,

IL-2, IL-1beta, IL-6. In particular, significant increases in the expression of IL-12 p70 were observed from mouse DCs derived from bone marrow in response to solubilized sporozoite antigen and the recombinant cryptosporidial antigens, Cp40 and Cp23. We observed a small but Z-IETD-FMK price significant increase in IL-18 expression following the exposure to Cp40. We found that the induction of Th1 cytokines was MyD88 dependent (MyD88 knockout mouse DCs were unresponsive). Additionally, both sporozoite preparations (solubilized and live) significantly

induced IL-12 production by human monocytic dendritic cells (MoDCs). This finding indicates that solubilized as well as recombinant antigens can induce the maturation of DCs and subsequently initiate an innate immune response. Cryptosporidium CDK inhibitor parvum (C. parvum) is a zoonotic intracellular opportunistic protozoan parasite with a worldwide distribution. Infection is usually transmitted from one host to another through faecal contamination of drinking water or food or by contact with infected hosts (1). Following ingestion, C. parvum infection develops in the intestinal tract of the host, followed by symptoms of diarrhoea, low-grade fever, nausea and weight loss (2). In immunocompetent individuals, the disease is typically self-limiting. However, in individuals who are immunocompromised, such as adult patients infected oxyclozanide with HIV as well as HIV-positive children, diarrhoeal disease can be persistent and life-threatening. Chronic disease

in immunodeficient hosts is exacerbated because of the lack of effective treatment options (3). To date, no effective treatment regimen nor preventive intervention has been developed for immunocompromised individuals, partly due to the incomplete understanding of the host immune response to the parasite infection (4). Studies pertaining to host cell–mediated immune responses indicate the importance of T lymphocytes, specifically CD4+ T cells during recovery from cryptosporidial infections (5). The cytokine IFN-γ also plays an important role in adaptive as well as in innate immune responses to C. parvum infection in mice (6). Secretion of pro-inflammatory cytokines such as IL-12 p70 is a key in generating IFN-γ and can be induced through the activation of antigen-presenting cells (APCs) by various pathogens and their products. One type of antigen-presenting cell, dendritic cells (DCs), plays an important role in eliciting an immune response and is also the first line of defence against pathogens by activating an innate immune response.