U. Grawunder et al., REARRANGEMENT AND EXPRESSION OF KAPPA LIGHT-CHAIN GENES CAN OCCUR WITHOUT MU HEAVY-CHAIN EXPRESSION DURING DIFFERENTIATION OF PRE-B CELLS, International immunology, 5(12), 1993, pp. 1609-1618
The kinetics of kappa light (kappaL) chain gene rearrangement and expr
ession on mRNA and protein level has been studied with four stromal ce
ll/IL-7 reactive, long-term in vitro proliferating pre-B cell lines an
d clones, two from fetal liver of normal mice and two from fetal liver
of EmuH-bcl-2 transgenic (bcl-2-tg) mice. These pre-B cell lines and
clones are DJH-rearranged on both H chain alleles. Two of the clones h
arbor H chain rearrangements which do not allow the expression of V(H)
DJ(H) rearranged H chain genes as muH chain proteins. Upon removal of
IL-7 from the pre-B cell cultures all four cell lines rearrange V(H)-D
J(H) and V(L)-J(L) gene segments, loose the surface expression of c-ki
t, CD43, and surrogate light chain, as well as the capacity to be clon
able on stromal cells in the presence of IL-7. Pre-B cells from normal
mice die by apoptosis during differentiation, while those from bcl-2-
tg mice do not. All four lines and clones express comparable levels of
mRNA for muH and kappaL chains with the same time kinetics during 3 d
ays of differentiation. However, only two of the four pre-B cell lines
and clones express muH chain protein, whereas all four pre-B cell lin
es and clones express kappaL chain protein at comparable levels betwee
n 2 X 10(5) and 1.4 x 10(6) kappaL chain molecules per cell. These res
ults suggest that muH chain expression is not mandatory for rearrangem
ent and normal expression of kappaL chain genes when pre-B cells diffe
rentiate to B cells.