Absence of C3, C5, and FcRγ does not impact autoantibody production in K/BxN mice. Serum levels of anti-GPI IgG were determined in C3-deficient K/BxN mice and controls (left panel), C3/FcRγ-deficient K/BxN mice and controls (middle panel), and C5/FcRγ-deficient K/BxN mice and controls (right panel). Control animals are indicated by filled bars and knockout mice by open bars. A405 indicates absorbance in the enzyme-linked immunosorbent assay. Data are mean ± standard error of the mean. There are no statistically significant differences between the anti-GPI levels. FcRγ, the cytoplasmic signaling chain shared by activating Fc receptors for immunoglobulin G; GPI, glucose-6-phosphate isomerase; IgG, immunoglobulin G.