Thymic maturation processes including MNC restriction and self-recogni
tion require intimate association of thymocytes and stromal cells. Com
pared to the thymic architecture of various ''normal'' control strains
of mice, defects in the thymic microenvironment have been demonstrate
d in New Zealand black (NZB) mice, Moreover, it is well known that NZB
(H-d(d)) mice, when crossed with NZW(H-2(u)) mice, (NZB x NZW)F1, disp
lay a unique spectrum of autoimmune disease manifestations, including
murine SLE, Using an extensive panel of monoclonal antibodies that def
ine the thymic microenvironment, we examined two additional strains of
(NZB x H-2(u))F1 mice: (NZB x C57BL/10.PL)F1 and (NZB x PL/J)F1 mice
to investigate the contributions of the 11-2 and non-H-2 loci to the t
hymic abnormalities previously documented to occur in murine lupus. NZ
B, NZW, and (NZB x NZW)F1 mice were studied concurrently as were two a
dditional control strains C57BL/6 and C57BL/10Sn. NZW mice had a norma
l thymic architecture as did the other H-2(u) mice and the control str
ains. In contrast, (NZB x NZW)F1 mice had a significantly altered thym
ic microenvironment; mild thymic abnormalities were also found in (NZB
x PL/J)F1 but not in (NZB x CB7BL/10.PL)F1. As expected, (NZB x NZW)F
1 mice developed elevated titers of autoantibodies to DNA, proteinuria
, and decreased life span. Interestingly, only (NZB x PL/J)F1 mice had
increased levels of IgM antibodies to dsDNA, but did not manifest IgG
anti-DNA or reduced survival, Defects in thymic stromal cells are ass
ociated directly to autoimmunity and their origin appears to be determ
ined by non-H-2 loci. (C) 1995 Academic Press, Inc.