In-frame κ light chain repertoire is more restricted in mature naive
B cells than in immature B cells from three Meg (VH186.2
transgenic × JH−/−) mice. κ light
chain joins to Jκ2 from immature (population E, white
bars) and mature (population F, black bars) B cell populations were
amplified, cloned, and sequenced. Each panel compares the in-frame
light chain repertoire of immature and mature splenic B cells from an
individual mouse. The horizontal axis is labeled with Vκ
families, and chain numbers as assigned by Strohal et
al. (15). Chains not identified by Strohal are labeled N1–N9.
The vertical axis depicts standardized κ light chain expression
frequency as a percentage of total κ chains sequenced.
(a) Vκ24/25 family member number 80
(marked with an asterisk) was found to be at a three-fold greater
percentage in mature (black bars) than immature (white bars) B cells
within the first mouse (E, n = 37; F,
n = 42). This Vκ24/25 family member also
represents the most common κ light chain in the mature B cell
population. (b) In the second mouse, the same
Vκ24/25 family member number 80 was found to be
enhanced at the E to F transition, representing 12% of total in-frame
Vκ chains in the mature B cell population and only 2% in
the immature population (E, n = 48; F,
n = 59). (c) In a third mouse
analyzed, the same Vκ24/25 family member number 80 once
again appeared at a much greater frequency in the mature B cell
population (12%) than the immature B cell population (2.5%) (E,
n = 40; F, n = 50).
(d) Tabulation of all Vκ-Jκ2
sequences from the Meg line for immature (E) and mature (F) cells is
shown. The horizontal axis is labeled with as above whereas the
vertical axis depicts total number of sequences with the immature
numbers normalized to be equivalent to the mature numbers
(n = 151 for both populations).
Vκ24/25 sequence 80 (marked with an asterisk)
represents just under 5 sequences of 151 in immature B cells (3.2%)
and represents 19 of 151 sequences (12.6%) in mature B cells. This
enhancement is highly significant (P < 0.003).