Blood, 1 March 2001, Vol. 97, No. 5, pp. 1511-1513
BRIEF REPORT
The diversity of rearranged immunoglobulin heavy chain variable
region genes in peripheral blood B cells of preterm infants is
restricted by short third complementarity-determining regions but not
by limited gene segment usage
Michael Zemlin,
Karl Bauer,
Michael Hummel,
Sabine Pfeiffer,
Simone Devers,
Cosima Zemlin,
Harald Stein, and
Hans T. Versmold
From the Department of Pediatrics and Pathology, Freie
Universität Berlin, Berlin, Germany.
The immunoglobulin diversity is restricted in fetal liver B cells.
This study examined whether peripheral blood B cells of extremely
preterm infants show similar restrictions (overrepresentation of some
gene segments, short third complementarity-determining regions
[CDR3]). DNA of rearranged immunoglobulin heavy chain genes was
amplified by polymerase chain reaction, cloned, and sequenced. A total
of 417 sequences were analyzed from 6 preterm infants (25-28 weeks of
gestation), 6 term infants, and 6 adults. Gene segments from the
entire VH and DH gene
locus were rearranged in preterm infants, even though the
DH7-27 segment was overrepresented (17% of rearrangements)
compared to term infants (7%) and adults (2%). CDR3 was shorter in
preterm infants (40 ± 10 nucleotides) than in term infants
(44 ± 12) and adults (48 ± 14) (P < .001) due to
shorter N regions. Somatic mutations were exclusively found in term
neonates and adults (mutational frequency 0.8% and 1.8%). We conclude
that preterm infants have no limitations in gene segment usage, whereas
the diversity of CDR3 is restricted throughout gestation.
