We have examined the contributions of Interleukin 4 (Ib4), IL-5, and other stimuli to the expression of Immunoglobulin G1 (IgG1) and IgE in murine B lymphoblasts activated with anti-Ig. The combination of IL-4 and -5 induced B lymphobhsts to proliferate and to secrete IgM and IgG1. However, an additional stimulus was required along with II:4 and -5 for induction of IgE secretion. This stimulus was provided by lipopolysaccharides (LPS) or cytokines produced by TC-1 or EL4 cells. In the absence of II.-5, exceptionally high concentrations of II.-4 (>1,000 U/ml) were required to elicit IgG1 and IgE secretion from B lymphoblasts cultured with either LPS or TC-l-conditioned media (CM). To investigate regulation of expression of γ1 and e genes by I1,4, -5, and LPS, the requirements for induction of 3’1 and e germline and productive transcripts were examined. Germline γ1, but not e, transcripts were detected in RNA from B lymphoblasts treated with Il-4 and -5 for 48 h. In contrast, both germline γ1 and e transcr pts could be detected in B lymphoblasts cultured with IL-4 and LPS, and steady state levels of germline γ1 transcripts were four- to sevenfold higher in blasts cultured with LPS and Ib4, compared with blasts cultured with IL-4 and -5. LPS enhanced steady state levels of germline transcripts induced by IL-4, but LPS did not promote substantial accumulation of productive γ1 and e transcripts. In contrast, IL-5 did not affect steady state levels of germline transcripts stimulated by IL-4, but did markedlyincrease levels of productive γ1 and e transcripts. Thus, ymphokines regulate two distinct events in isotype switching: induction of germline transcripts (IL-4), and production of VDJ-C γI and VDJ-Ce mRNA (IL_5), which leads to secretion of IgG1 and IgE. © 1992, Rockefeller University Press., All rights reserved.
Purkerson, J. M., & Isakson, P. C. (1992). Interleukin 5 (IL-5) Provides a Signal That Is Required in Addition to ID4 for Isotype Switching to Immunoglobulin (Ig) G1 and IgE. Journal of Experimental Medicine, 175(4), 973–982. https://doi.org/10.1084/jem.175.4.973