Time course studies on rat IgE production in N. Brasiliensis infection

We present here a study of the relationship in time between the elevation of total serum IgE, the parasite-specific IgE response, and the potentiated IgE response to unrelated antigen which occurs in rats following infection with the worm parasite N. brasiliensis. During a first infection the potentiated IgE response (to egg albumin) and elevation of total IgE occur synchronously rising to a peak on days 12-14 after infection, with the fastest rate of increase occurring between days 8 and 10. N. brasiliensis-specific IgE rises to a peak some 2-3 weeks later when both total IgE and the potentiated response have largely declined. A strain difference is shown in that Wistar rats produce far lower levels of total and parasite-specific IgE than Hooded Listers. Events following reinfection differ in that total IgE rises more rapidly, very high levels being reached 6 days after reinfected together with a secondary specific IgE response to N. brasiliensis. The total IgE level, however, rises by a far greater factor than parasite-specific IgE and declines rapidly while the parasite-specific response declines slowly over many weeks. The egg albumin response is not repotentiated. It is proposed that the total IgE response and the potentiated IgE response which forms a small component of it results from the release of a non-specific IgE-stimulating factor produced by N. brasiliensis-specific T cells. In this scheme the same or similar cells are involved in the production of N. brasiliensis-specific IgE through a separate specific helper function.