Defective cytokine and Ab responses in T. muris-infected ICOS-/- mice. BALB/c and ICOS-/- mice were infected with T. muris eggs, and after 18 days of infection serum, mLN and guts were harvested. mLN were restimulated with parasite Ag, and supernatants were harvested and measured for the production of IL-4 (a), IL-13 (b), and IFN-γ (c). T. muris-specific IgG1 reciprocal end-point dilution (r.e.d.) (d) and total IgE (e) levels were measured by ELISA. Worm burdens (f) were counted from the large intestine as described in Materials and Methods. Data shown are means of at least three mice and are representative of at least three individual experiments. Significance within experiments (b-f) and across experiments (a) where p < 0.05 is illustrated by *.