Antibody to immunoglobulin G and polyethylene glycol augment cyclic adenosine monophosphate production by TSH receptor antibody bound to porcine thyroid cells.

Anti-immunoglobulin G (IgG) augments cyclic adenosine monophosphate (cAMP) production by thyroid-blocking antibody (TBAb) bound to porcine thyroid cells (PTC). This is described as a conversion phenomenon. We reported the effect of polyethylene glycol (PEG) to augment thyroid-stimulating antibody (TSAb) activity in a PTC assay. In the present experiment we examined the effect of anti-immunoglobulin G (IgG) and PEG on cAMP production from TBAb or TSAb bound to PTC. TBAb bound to PTC was separated from unbound TBAb by centrifugation after a first incubation (0.5 hour at 37°C) of TBAb-IgG with PTC. TBAb bound to PTC were incubated with anti-human (h)IgG or hIgG fragments [F(ab′)2, Fc, Fd, H chain or L-chain] for 4 hours at 37°C in the second incubation. Anti-IgG or anti-IgG fragments increased cAMP production. No conversion was caused by protein A, protein L, or PEG (5%). PEG did not augment cAMP production by these IgG antibodies. PEG augmented cAMP production during incubation of TSAb-IgG bound to PTC, but...