IL5 and severe combined immunodeficiency: Conversely, secretion of IL-5, a pivotal effector Th2 cytokine, was highly elevated in TNFi∆ARE/i∆ARE → SCID mice (TNFi∆ARE/i∆ARE → SCID = 647 ± 192 pg/ml vs. wt → SCID mice = 13.6 ± 0.4 pg/ml, P<0.01).