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

Abstract

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 × 10⁶ 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 individual 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.