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.
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 V(H) and D(H) gene locus were rearranged in preterm infants, even though the D(H)7-27 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.
Department of Pediatrics and Pathology, Freie Universität Berlin, Berlin, Germany.
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M
Zemlin
K
K
Bauer
M
M
Hummel
S
S
Pfeiffer
S
S
Devers
C
C
Zemlin
H
H
Stein
H T
HT
Versmold
D000328:Adult; D001483:Base Sequence; D022801:Complementarity Determining Regions; D005312:Fetal Blood; D015322:Gene Rearrangement, B-Lymphocyte / Q000235:genetics*; D005803:Genes, Immunoglobulin; D014644:Genetic Variation; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood / Q000276:immunology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction
D022801:Complementarity Determining Regions; D007135:Immunoglobulin Variable Region