| Abstract: | The concentration of IgE in the serum of Sprague-Dawley rats increased after infection with Nippostrongylus brasiliensis (NB). The IgE concentration in normal rats was less than 1 mug/ml. After re-infection with NB, the concentration increased in 100 to 300 mug/ml. Mast cells were purified from peritoneal cells of both normal and NB-infected animals. Purified mast cells from the infected animals released histamine upon exposure to NB antigen. The antibody specific for IgE released histamine from purified mast cells of both normal and infected animals. Dose-reponse curves of histamine release suggested that mast cells from NB-infected animals bear more IgE molecules than normal mast cells. Binding of 125I-labeled rat E myeloma protein with normal mast cells was demonstrated by autoradiography. Under the same experimental conditions, mast cells of infected animals were not labeled with 125I-IgE. Mast cells from both normal and infected animals failed to combine 125I-labeled IgG. The number of IgE molecules bound per mast cell was determined by incubating 125I-labeled IgE with purified mast cells. When mast cells were incubated incubated in 0.6 to 2 mug/ml of IgE, the number of IgE molecules combined with the mast cells from infected animals was about 10% of that bound with normal mast cells. The results indicated that a large proportion of IgE receptors on mast cells of infected animals was occupied by their own IgE. No significant difference was observed between normal mast cells and those of infected animals with respect to histamine content and intracellular levels of cyclic nucleotides. |
