IgE formation in the rat following infection with Nippostrongylus brasiliensis. III. Soluble factor for the generation of IgE bearing lymphocytes

Normal rat bone marrow cells incubated with serum or lymph from Nippostrongylus brasiliensis (Nb)-infected rats showed an increase in the proportion of IgE-bearing cells in culture. This effect was produced in a similar fashion by cell-free supernatants (CFS) from cultures of mesenteric lymph node cells obtained from Nb-infected rats. The action of CFS on bone marrow cells appeared to be specific for the generation of IgE-bearing cells since the proportion of IgM-bearing cells in the culture did not change. The IgE-bearing cells in bone marrow cell cultures consisted of small lymphocytes, blast cells, and mast cells, and the addition of CFS to the cultures predominantly increased the number of IgE-bearing blast cells. CFS was also effective in increasing the proportion of IgE-bearing small lymphocytes in cultures of normal mesenteric lymph node cells. Removal of the IgE in CFS by an anti-IgE immunosorbent did not affect the ability of CFS to generate IgE-bearing cells. The factor(s) in CFS responsible for this activity was shown to migrate with serum β-globulins in zone electrophoresis and to possess a molecular size of between 10⁴ and 2 x 10⁴ m.w. The ability of CFS to generate IgE-bearing cells was diminished by treatment with the enzymes trypsin and ribonuclease A, but was unaffected by chymotrypsin.