title: Characterization of the primary IgM response to GAT and GT: conditions required for the detection of IgM antibodies.
abstract: Primary IgM antibody responses to synthetic linear copolymers of L-glutamic acid, L-tyrosine, and L-alanine were investigated. The appearance of primary IgM anti-GAT antibodies was detected in BALB/c mice by using a solid phase radioimmunoassay (SPRIA) procedure. The finding was verified for GAT in responder mice and GAT-MBSA and GT-MBSA in nonresponder mice in an indirect plaque forming cell (PFC) assay by using a rabbit antiserum directed against the mulambda myeloma protein, MOPC 104E. Facilitated IgM PFC could be inhibited by a purified muK myeloma protein, TEPC 183. Maximal facilitated IgM plaque response was found to precede the IgG response by several days. A direct plaque assay was developed for the detection of IgM anti-GAT plaques using poly-L-lysine (PLL) to couple GAT to sheep erythrocytes (SRBC). GAT-SRBC coupled by the PLL method optimally couple 4 to 5 times less antigen to the indicator cell surface than does the CrCl3-coupling method routinely employed in our laboratory. These findings were extended to a conventional antigen, chicken gamma globulin (CgammaG). We found that a less dense epitope coat on the indicator cell surface favors detection of direct IgM PFC, whereas a more densely coated indicator cell favors the detection of facilitated IgM and IgG PFC responses.
mesh_terms: D000409:Alanine / Q000276:immunology*; D000818:Animals; D000917:Antibody Formation; D002645:Chickens; D004912:Erythrocytes / Q000276:immunology; D005971:Glutamates / Q000276:immunology*; D006462:Hemolytic Plaque Technique; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007700:Kinetics; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D011817:Rabbits; D011863:Radioimmunoassay; D012756:Sheep; D014443:Tyrosine / Q000276:immunology*; D005719:gamma-Globulins / Q000276:immunology
chemical_list: D005971:Glutamates; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D005719:gamma-Globulins; D014443:Tyrosine; D000409:Alanine