DIFFERENTIATION OF B-LYMPHOCYTE IN HUMAN GAMMA-CHAIN TRANSGENIC MICE

Transgenic mice were produced by the introduction of cloned human gamma-1 heavy chain immunoglobulin (Ig) gene. The human gamma-1 chain gene was expressed in a B cell-specific manner and the level of expression increased by treatment of spleen cells with bacterial lipopolysaccharide. Human gamma chain expression did neither prevent VDJ rearrangement of the mouse endogenous heavy chain gene, nor class switching from the mu to gamma constant region, although the human gamma chain was associated with the mouse light chain to form a complete Ig G molecule. No B cells produced only huma chain, instead they produced only mouse Ig or both mouse Ig and human chain. All hybridoma cell lines obtained from transgenic mice produced both mouse Ig and human chain. All these results suggest that successful mouse endogenous mu chain expression is a prerequisite for B cell differentiation.