Induction of Treg Cells

Chronic infections such as HIV result in immunosuppression as a result of induction of CD4+ Treg cells. Increased risk of Kaposi s sarcoma, non-Hodgkin s lymphoma and liver cancer is associated with long-term infections such as HIV. Immunosuppression in HIV-infected individuals occurs before the development of AIDS, which proceeds before the depletion of CD4+ T cells, and the induction of Treg cells may play a role in this process. The mechanisms are IL-10-independent and include the involvement of TGF-(3 secreted via signaling through cell-cell interaction involving CTLA-4. 

Regulatory T Cells Suppress DC Maturation As outlined above, several lines of evidence indicate that DCs are crucially involved in the induction of Tregs. However, this interaction is not restricted to a DC-to-Treg one-way street, since several recent data revealed that Tregs in turn have an impact on DC development [11]. 

Suppression of the DTH Response The induction and regulation of CD8+ Tregs in vivo is complex and dependent on several cell types [2,3], In vivo, the induction of CD8-I- suppressor T cells required Lyt-l-l- (CD4) suppressor-inducer T cells that did not directly suppress DTH. The mechanism of this induction was not clear but appeared to be mediated by antigen-specific, soluble molecules produced by the suppressor-inducer T cells [18]. Additionally, the in vivo induction of CD8+ suppressor T cells requires cells sensitive to the cytotoxic effects of cyclophosphamide [19,20]. 

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