EVALUATION OF THE EFFECTIVENESS OF 3 IMMUNOGLOBULIN-G (IGG) REMOVAL PROCEDURES FOR ROUTINE IGM SEROLOGICAL TESTING

Three procedures for the removal of immunoglobulin G (IgG) from human serum were evaluated for their effectiveness in eliminating false-posi tive results caused by rheumatoid factor and in removing IgG from seru m to reduce competing-IgG interference in IgM enzyme-linked immunosorb ent assay (ELISA) testing. The procedures investigated employed two an ti-human IgG diluents and a recombinant protein G-filled tube, The ant i-human IgG was more effective than the protein G method in eliminatin g false-positive results caused by rheumatoid factor and removed 5.4% more IgG from serum samples in the normal range (<1,700 mg/dl) and up to 16.4% more of the IgG from samples with elevated levels (>1,700 mg/ dl), The recombinant protein G removed less IgM than the anti-human Ig G diluents; however, this difference did not affect the results of the ELISA. For these reasons, the in-house-developed anti-human IgG dilue nt proved to be the most effective and economical for IgM serological testing.