In these studies we have determined the molecular weights of B cell growth factor (BCGF) (< 20,000), and B cell differentiation factors (BCDF) that induce immunoglobulin M (IgM) secretion (BCDF(μ)) (30-60,000) and IgG secretion (BCDF(γ)) (< 20,000). Thus, the molecular weight of BCDF(μ) is distinct from that of BCGF and BCDF(γ); BCGF and BCDF(γ) cannot be distinguished. In addition, BCGF, BCDF(μ), and BCDF(γ) are distinguishable by their presence or absence in different supernatants from a panel of mitogen-induced T cell clones. These results suggest that the three lymphokines are different. This conclusion is supported by their differential biological effect on B cells from adult and neonatal mice. Thus, treatment with anti-Ig induces B cells from adult mice to proliferate and this proliferation is sustained by BCGF. In contrast, even in the presence of BCGF, anti-Ig does not induce B cells from neonatal mice to proliferate. However, BCDF(μ) and BCDF(γ) induce IgM and IgG secretion in B cells, respectively, from both adult and neonatal mice. Thus, mature B cells can both clonally expand and differentiate in response to anti-Ig, BCGF, and BCDF, whereas immature B cells can only differentiate. The poor response of neonatal B cells to anti-Ig and BCGF may partially explain the relative immunoincompetence of immature B cells.
|Original language||English (US)|
|Number of pages||13|
|Journal||Journal of Experimental Medicine|
|Publication status||Published - 1983|
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