Delineation of producing ability of IgG and IgA subclasses by naive B cells in newborn infants and adult individuals.
Neonatal B cells with the naive (sIgD+) phenotype are able to generate IgG- and IgA-producing cells as well as IgM production in the presence of memory CD4+ T cells expressing L-selectin (CD62L) in pokeweed mitogen-stimulated cultures. We used this system to examine comparatively the ability of naive B cells to produce IgG and IgA subclasses in newborn infants and adult individuals. Naive B cells were enriched from both donors on the basis of sIgD positivity, and memory (CD45RO+) CD4+ T cells with CD62L expression were isolated from adults. We here demonstrate some differences in profiles of IgG and IgA subclass production between neonatal and adult naive B cells. In neonatal B cells, IgG1 and IgG3 were predominantly produced, but IgG2 and IgG4 production was virtually absent. Similar to neonatal B cells, adult naive B cells produced mainly IgG1 and IgG3, although memory (sIgD-) B cells from adults secreted all of the IgG subclasses. It should be noted that low but detectable levels of IgG2 and IgG4 were found in adults' naive B cell cultures. Although IgA produced by neonatal B cells was exclusively IgA1, IgA2-secreting cells were identifiable in adult naive B cells. The results suggest that further class switch of naive B cells to IgG2, IgG4 and IgA2 in addition to IgG1 and IgG3 may be controlled by their own age-dependent maturation process.
Yachie
A
A
Department of Paediatrics, School of Medicine, Kanazawa University, Ishikawa, Japan.
Konno
A
A
Ohta
K
K
Wada
T
T
Seki
H
H
Taniguchi
N
N
Miyawaki
T
T
D000328:Adult; D001402:B-Lymphocytes / Q000378:metabolism*; D002478:Cells, Cultured; D005312:Fetal Blood / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000096:biosynthesis* / Q000145:classification; D007072:Immunoglobulin D / Q000032:analysis; D007074:Immunoglobulin G / Q000096:biosynthesis* / Q000145:classification; D007231:Infant, Newborn; D019041:L-Selectin / Q000032:analysis
D007070:Immunoglobulin A; D007072:Immunoglobulin D; D007074:Immunoglobulin G; D019041:L-Selectin