The aggregation of soluble ANTIGENS with ANTIBODIES, alone or with antibody binding factors such as ANTI-ANTIBODIES or STAPHYLOCOCCAL PROTEIN A, into complexes large enough to fall out of solution.

Synonyms: Precipitations, Immune, Co Immunoprecipitation, Immune Precipitations, Co-Immunoprecipitations, Immunoprecipitation, Precipitation, Immune, Immune Precipitation, Co-Immunoprecipitation