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Y Valles-Ayoub, HL Govan and J Braun
Department of Pathology, UCLA School of Medicine 90024-1732.
Childhood is a critical period for the development of the memory B-
lymphocyte repertoire necessary in protective humoral immunity. This study
addressed the natural history of memory B cells based on the previous
identification of germinal center and mantle zone cells as the probable
precursor and mature memory cell populations, respectively. Using flow
cytometric quantitation of these B-cell subpopulations in human tonsil, we
found that germinal center cells were abundant (70% of tonsil B cells)
during early childhood (2 to 3 years), but decline by early adolescence (8
to 14 years) to a low level (33%, P = .0003). To study the clonal evolution
of these B-cell subpopulations, germinal center and mantle zone B cells
were isolated using a preparative magnetic immunobead method, and analyzed
using a novel polymerase chain reaction-based quantitative assay to measure
the abundance of B-cell clones bearing certain rearranged VH subfamilies.
Two VH subfamilies were informative: VH1N clones were uniquely deficient in
germinal center B cells at the early age period, but became abundant in
later childhood; and VH3L clones were absent among germinal center cells
regardless of age. In contrast, B-cell clones bearing each VH subfamily
were abundant in the mantle zone subpopulation throughout childhood. These
findings suggest that the abundance and clonal pattern of germinal center B
cells evolves during childhood, presumably due to changing antigenic or
ontogenic processes. Moreover, the distinct clonal pattern of germinal
center versus mantle zone B cells suggests that a major phase of clonal
selection occurs after germinal center emigration.
This article has been cited by other articles:
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| Copyright © 1990 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
