IL-13 Transgene State Impairs Mycobacterial (Type-1) and Schistosomal (Type-2) Antigen-Elicited Responses

Transgenic technology provides one approach for examining cytokine properties in vivo. This study directly tested the effect of a lung-targeted IL-13 transgene on the induction and elicitation of Th1 and Th2 cell-mediated immuno-inflammatory responses. Induction of Th1 (type 1) and Th2 (type 2) responses were tested by sensitization of IL-13 transgenics and littermates with purified protein derivative (PPD) of Mycobacterium bovis or Schistosoma mansoni eggs. Secondary elicitation of pulmonary granulomas was examined in adoptively sensitized transgenics and littermates challenged with bead-bound PPD or S. mansoni egg antigens. Parameters included lymphoid tissue cytokine profiles and granuloma sizes. Results showed that induction and elicitation of both type 1 and type 2 cytokines and granulomas were significantly abrogated in transgenics. Systemic effects were possible, as transgenic serum contained high levels of circulating IL-13. These findings support the concept that IL-13 impairs effector functions and provide novel information regarding its role in regulating Th2 cytokines.