IL-11 directs Th2 polarization by increasing IL-4 and decreasing IFN-γ⁺ cells.

Highly purified CD4⁺CD45RA⁺ naive T cells were stimulated with plate-coated anti-CD3 and soluble anti-CD28 MoAbs in the presence or the absence of IL-11 or IL-4. In neutralization experiments, specific anti–IL-11 or anti–IL-4 antibodies or isotype controls were added to the culture. After 6 days of culture, T cells were transferred to uncoated plates and expanded with recombinant human IL-2 for 7 to 8 days. T cells were then stimulated with PMA and ionomycin and stained for intracellular cytokine content. IL-4⁺ cells were increased by the addition of IL-11 from a mean value of 2% to 12% (n = 3; P < .05), whereas IFN-γ⁺ cells diminished from 30% to 21% (n = 3;P < .05). Addition of anti-IL-11 antibodies reversed the results. When IL-11 was replaced by IL-4, a similar pattern of Th2 polarization was observed. An experiment representative of 3 is shown here.