Phagocytosis and degradation of DNA-anti-DNA complexes by human phagocytes: influence of the antibody class.

DNA-anti-DNA complexes were prepared with igG anti-DNA or IgM anti-DNA and incubated with monocytes and neutrophils from human blood. The capacity of the complexes to induce phagocytosis and degradation of the antigen by the phagocytes varied with the composition of the complexes. Complexes prepared with IgG anti-DNA were readily processed (phagocytosed and degraded) by the cells, provided the complexes were large (precipitating at 3000 x g in 15 minutes). Processing of the complex required the Fc part of the IgG antibody. Complexes prepared with IgM anti-DNA were hardly processed at all, although they were as large as the IgG anti-DNA-containing complexes that were processed. IgM anti-DNA enhanced the processing of IgG anti-DNA-DNA complexes by increasing the size of the complexes.