The loss of Fc γ-chain reduces the IL-6 level in the sera of SHIP^−/− mice. Serum IL-6 levels of SHIP^−/−, SHIP, μMT, and SHIP, γ-chain double-knockout mice at the age of 8 weeks. The serum was obtained by cardiac puncture, and IL-6 level was determined by ELISA. Results from 8 mice of SHIP^−/− and SHIP, γ-chain double-knockout and 3 mice of SHIP, μMT double-knockout each strain are indicated as pictograms per milliliter.