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 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 × 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.

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This work was supported by Research Grants PCM-74-00837 from the National Science Foundation, AI-10060 from United States Public Health Service, and from John A. Hartford Foundation. This is Publication No. 270 from the O'Neill Laboratories at the Good Samaritan Hospital.

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