IL18R1 and infection: Nevertheless, IL-12Rβ1− and IL-2R− (CD25−) Th1 cells from WSX-1−/− mice (day 14 of infection) responded poorly to IL-12 and IL-2 activation, confirming the functional relevance of increased cytokine receptor expression by Th1 cells in WSX-1−/− mice (results not shown).