SummaryPurification of a murine IgG3 monoclonal antibody (Mab 22) directed against an epitope ofChlamydia‐specific lipopolysaccharide by affinity chromatography on recently described solid phase IgG Fc‐receptors fromStreptococcus dysgalactiaeis reported. SDS‐PAGE studies revealed the purity of the eluted antibody. The purified Mab 22 was characterized by determination of class, subclass and light chain‐type, and by dot tests and immunoblot a