SHIP^−/− mice had a high level of total and aggregated IgG in peritoneum. (A) Total IgG obtained by ELISA in peritoneal lavages of WT and SHIP^−/− mice. (B) The lavage fluid was centrifuged 55 000g, and IgG (defined as aggregated IgG) was measured in the pellet. (A-B) The data were obtained from 6 individual mice, and each point represents a single animal. (C) IgG production from peritoneal cells was determined by ELISA. The F4/80⁺ macrophages were removed, and the remaining cells were cultured for 24 hours. Cells were collected, and secreted IgG was measured by ELISA from 9 individual mice.