Characterization of lymphoproliferation induced by interactions between lprcg and gld genes.

The lprcg gene is the novel mutation at the lpr locus characterized by its complementary to the gld gene in induction of lymphoproliferation in the mouse. Because of the potential usefulness of mice with this mutation in studies on the interrelationship between lpr and gld, we were urged to characterize the lymphoproliferative disease developing in (CBA/K1Jms-lprcg/lprcg x C3H/HeJ-gld/gld) F1 hybrid (lprcg-gld) mice. Despite the milder lymphadenopathy in the lprcg-gld mice, the expanding lymph node cells showed the same surface marker pattern as that in C3H/HeJ-lpr/lpr, C3H/HeJ-gld/gld, and CBA/K1Jms-lprcg/lprcg mice, characterized by the positivity for Thy-1, B220, Ly-6, and Ly-24, and the negativity for L3T4, Lyt-2 (hence designated double-negative cells), and sIg. Furthermore, these cells proved to be of a T-cell lineage based on the rearrangement of the TCR beta-chain gene, the same as the already known double-negative cells. Noticeably, in lprcg-gld mice, serum IgG and autoantibodies of the IgG class were not elevated at an early age but were slightly elevated at an advanced age despite early elevation of the serum IgM and IgM autoantibodies. These results suggest that the lymphoproliferative mice carrying lprcg and gld genes in a heterozygous state will serve as a new tool for inquiring into the interrelationship among lpr, gld, and lprcg.