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 of radioimmunoassay (SPRIA) procedure. This 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 μλ myeloma protein, MOPC 104E. Facilitated IgM PFC could be inhibited by a purified μκ 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 (CγG). 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.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Immunology|
|State||Published - Jan 1 1979|
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