Sequence analysis of the germ-line VH gene corresponding to a nephritogenic antibody in MRL/lpr lupus mice

In order to investigate the genetic origin of nephritogenic antibodies in MRL/Mp-lpr/lpr (MRL/lpr) lupus mice, we isolated the germ-line heavy chain variable region (V(H)) gene corresponding to the nephritogenic antibody, B1, derived from an unmanipulated MRL/lpr mouse. Injection of this antibody into C.B-17/Icr-scid/scid mice resulted in the generation of wire loop-like glomerular lesions resembling those of lupus nephritis. Nucleotide sequences of this germ-line V(H) gene showed no replacement mutation in the V(H) region of the B1 antibody. Furthermore, this gene was identical to that found in the C3H/HeJ-lpr/lpr strain of mice. Our results suggest that germ-line V(H) genes can encode nephritogenic antibodies without somatic mutation, even in a mouse strain not prone to lupus.