Da. Fulcher et A. Basten, REDUCED LIFE-SPAN OF ANERGIC SELF-REACTIVE B-CELLS IN A DOUBLE-TRANSGENIC MODEL, The Journal of experimental medicine, 179(1), 1994, pp. 125-134
The life span of anergic self-reactive B cells was determined by 5-bro
mo-2'-deoxyuridine (BrdU) loading of tolerant double-transgenic (Dbl-T
g) mice produced by mating hen egg lysozyme (HEL)-transgenic mice with
the corresponding immunoglobulin-transgenic (Ig-Tg) mice, the B cells
of which express anti-HEL IgM and IgD. B cells from Dbl-Tg mice, desp
ite being exposed to soluble antigen throughout their development, are
not deleted, but persist in an anergic state. As a prelude to studyin
g the life span of these anergic B cells, BrdU was administered to non
transgenic mice; B cells from the bone marrow, spleen, and lymph nodes
displayed distinct kinetic profiles based on reciprocal expression of
the B220 isoform of CD45 and heat-stable antigen (HSA). Thus, immatur
e B220(lo)/HSA(hi) B cells incorporated BrdU rapidly suggesting recent
generation from dividing precursors, whereas uptake by B cells expres
sing the mature B220(hi)/HSA(lo) phenotype was significantly slower, c
onsistent with a longer life span. Such gating allowed analysis to be
directed at the stable mature B cell population in transgenic mice. Co
mparison of BrdU uptake in Ig- and Dbl-Tg mice indicated that B cells
from Dbl-Tg mice were renewed at a much higher rate (50% renewal times
of 0.64 vs. 3.4 wk for total B cells, and 1.2 vs. 5.0 wk for mature B
200(hi)/HSA(lo) cells from Dbl- and Ig-transgenic mice, respectively).
This difference was even more marked when analysis in Dbl-Tg mice was
restricted to HEL-binding cells, which had a 50% renewal time of 3-4
d compared with 4-5 wk for non-HEL-binding B cells. While the proporti
on of B cells in cell cycle, and the rate of entry of newly generated
B cells into the spleen of Ig- and Dbl-Tg mice, were similar, B cell n
umbers were reduced in Dbl-Tg mice. It was therefore concluded that an
ergic B cells have a markedly decreased life span in the periphery. Ac
cording to studies in radiation chimeras produced by reconstituting HE
L-transgenic recipients expressing different serum levels of antigen w
ith Ig-Tg bone marrow, the reduced life span of anergic B cells was as
sociated with the anergic state per se, the serum concentration of HEL
being important only in attaining the critical threshold necessary fo
r tolerance induction. B cells rendered tolerant by exposure to solubl
e self-antigen therefore survive for a relatively short period in an a
nergic state once they have reached peripheral lymphoid tissue and fai
l to enter the long-lived compartment. These findings have implication
s for the maintenance of self-tolerance and induction of autoimmunity
in both B cell and T cell repertoires and suggest that the distinction
between B cell anergy and deletion is more relative than absolute.