A reinterpretation of the evidence for an interaction between Clq and pairs of immunoglobulin molecules in an immune lattice.

An error in a previous article [Cohen S. (1968) J. Immun. 100, 407-413] was discovered which invalidates it as evidence that IgG immune complexes activate the classical complement pathway by an interaction involving pairs of antibody molecules, so-called doublet formation. The error concerns the correction to be made for the observed 8% residual activity of the modified antibody preparation used. When appropriate correction factors are applied, the data are found not to be consistent with the hypothesis of doublet formation. The analysis presented here has no bearing on the original article's experimental techniques, nor on its demonstration of co-operation between IgG molecules during complement fixation.