The enumeration of rat IgE-secreting cells using a reverse plaque-forming cell assay

A reverse hemolytic plaque assay utilizing protein A-coated sheep red cells and a specific rabbit anti-rat IgE preparation has been adapted for the enumeration of rat IgE-secreting cells derived from the IR-162 rat plasmacytoma and from rats infected with Nippostrongylus brasiliensis. Under optimal conditions, approximately 10-15% of the viable plasmacytoma cells were scored as plaque-forming cells. In rats infected with 5000 Nippostrongylus brasiliensis larvae, a maximum of 2 x 10(6) IgE-secreting cells were found in the mesenteric lymph nodes, and no IgE plaque-forming cells in their spleens. The kinetics of the mesenteric lymph node plaque-forming cell responses closely coincided with total serum IgE levels, with maximum responses occurring 15-16 days after infection. There was a high degree of correlation between the mesenteric lymph node IgE plaque-forming cell responses and total serum IgE levels of individuals rats. It was concluded that the IgE-secreting cells in the mesenteric lymph nodes contributed, in a large way, to the elevated levels of IgE found in the circulation of these rats.