POLYINOSINIC ACID - POLYCYTIDYLIC ACID PROMOTES T-HELPER TYPE-1 SPECIFIC IMMUNE-RESPONSES BY STIMULATING MACROPHAGE PRODUCTION OF INTERFERON-ALPHA AND INTERLEUKIN-12

The effects exerted on the development in vitro of Dermatophagoides pt eronyssinus group I (Der p I)-specific T cell lines and T cell clones by addition of polyinosinic acid:polycytidylic acid (poly I:C) in lymp hocyte bulk culture were examined. Der p I-specific T cell lines gener ated in presence of poly I:C exhibited reduced ability to produce inte rleukin (IL)-4 and IL-5 and developed into Der p I-specific CD4(+) T c ell clones showing a T helper (Th) type 0 or Th1, instead of Th0/Th2 c ytokine profile. This effect was prevented by addition to lymphocyte b ulk cultures of a mixture of antibodies specific for interferon (IFN)- alpha and IL-12, whereas the addition of anti-IFN-alpha or anti-IL-12 antibody alone was uneffective. Poly I:C also showed the ability to st imulate the production of noticeable amounts of both IFN-alpha and IL- 12 by human monocytes. Taken together, these data suggest that poly I: C is a Th1-inducing agent whose activity is mediated by its ability to stimulate the production of IFN-alpha and IL-12 by monocytes.