Activation of the γ1 gene by lipopolysaccharide and T cell-derived lymphokines containing a B cell differentiation factor for IgG1 (BCDFγ)

By using both pulse labeling of nascent RNA chains and lactoperoxidase-catalyzed cell surface radioiodination, we examined both the de novo synthesis of mRNA for γ-chains and the expression of membrane IgG (mIgG) on cells which had been stimulated with LPS plus a T cell supernatant (SN) containing a B cell differentiation factor for IgG1 (BCDFγ). Our results show that neither nascent mRNA for γ1 chains nor mIgG1 can be detected in B lymphocytes until they have been stimulated by both LPS and BCDFγ-containing T cell SN, and suggest that cell surface expression and secretion of IgG1 are coordinately controlled.