Am. Hamilton et Jf. Kearney, EFFECTS OF IGM ALLOTYPE SUPPRESSION ON SERUM IGM LEVELS, B-1 AND B-2 CELLS, AND ANTIBODY-RESPONSES IN ALLOTYPE HETEROZYGOUS F1-MICE, Developmental immunology, 4(1), 1994, pp. 27-41
IgM allotype heterozygous F1 mice were independently suppressed for Ig
h6a or Igh6b to evaluate the contribution of B-1 and B-2 cells to natu
ral serum IgM levels and Ab responses. B-2 B cells expressing IgM of t
he suppressed allotype were evident in the spleens of suppressed mice
4 to 6 weeks after cessation of the suppression regimen, whereas B-1 B
cells of the suppressed allotype were undetectable for up to 9 months
. Although serum IgM of the suppressed allotype was initially depleted
in mice suppressed for either allotype, by 7 months of age, there wer
e detectable levels of IgM of the suppressed allotype in the serum; ho
wever, the levels were significantly below that found in nonsuppressed
mice. When mice were immunized with either the T-independent or T-dep
endent form of phosphorylcholine, those suppressed for either allotype
, and consequently depleted of B-1 B cells of that allotype, did not r
espond with phosphorylcholine-specific IgM of the suppressed allotype.
In contrast, when mice were immunized with alpha 1-3 dextran, the Igh
6a allotype-suppressed mice were able to produce dextran-specific IgM
of that allotype. These results show that allotype-bearing B-1 cells o
f both allotypes can be effectively suppressed by this suppression pro
tocol and this produces long-lasting effects on B-1 cell levels and se
rum IgM of the suppressed allotype. These observations reflect the der
ivation of the majority of B-1 cells from fetal-neonatal precursors, w
hich cannot be replaced by newly emerging B-2 cells of adult origin. T
heir ablation by antibody treatment results in permanent alterations t
o the adult B-cell repertoire.