title: Efficient induction of immunoglobulin production in neonatal naive B cells by memory CD4+ T cell subset expressing homing receptor L-selectin.
abstract: The humoral response in newborns is mainly restricted to IgM production, which may be attributable to the naive nature of both B and T cells at birth. In light of the current evidence that memory (CD45RO+) CD4+ T cells help B cell differentiation, the present study was undertaken to examine whether a specified population within memory CD4+ T cells could induce the maturation of neonatal naive B cells. In the conventional PWM-stimulated cultures, the generation of IgG- and IgA-producing cells in addition to IgM production by neonatal B cells was significantly enhanced by co-cultures with memory, but not naive, CD4+ T cells. Memory CD4+ T cells were further divided into two populations based on expression of homing receptor L-selectin. These memory CD4+ T cell subpopulations appeared to behave in different fashions concerning help for Ig production by naive (sIgD+) and mature (sIgD-) B cells. L-selectin-negative memory CD4+ T cells exhibited helper function for Ig secretion by mature B cells. Intriguingly, Ig production by neonatal B cells as well as adult naive B cells, although less than that by mature B cells, was efficiently promoted by L-selectin-positive memory CD4+ T cells rather than L-selectin-negative ones. The results suggest that the capability of neonatal naive B cells to secrete IgG and IgA can be elicited by appropriate T-cell signals, especially from the L-selectin-positive population within memory CD4+ T cells, seemingly indicating its possible role for isotype switching in B cells.
authors.affiliation: Department of Pediatrics, School of Medicine, Kanazawa University, Ishikawa, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tsuji
authors.forename: R
authors.initials: R
authors.lastname: Nibu
authors.forename: K
authors.initials: K
authors.lastname: Iwai
authors.forename: H
authors.initials: H
authors.lastname: Kanegane
authors.forename: A
authors.initials: A
authors.lastname: Yachie
authors.forename: H
authors.initials: H
authors.lastname: Seki
authors.forename: T
authors.initials: T
authors.lastname: Miyawaki
authors.forename: N
authors.initials: N
authors.lastname: Taniguchi
mesh_terms: D000328:Adult; D000375:Aging / Q000276:immunology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D015815:Cell Adhesion Molecules / Q000276:immunology*; D002454:Cell Differentiation; D002648:Child; D006801:Humans; D017578:Immunoglobulin Class Switching; D007072:Immunoglobulin D / Q000378:metabolism; D007136:Immunoglobulins / Q000096:biosynthesis*; D007156:Immunologic Memory; D066298:In Vitro Techniques; D007231:Infant, Newborn; D019041:L-Selectin; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D016201:Receptors, Lymphocyte Homing / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology
chemical_list: D015815:Cell Adhesion Molecules; D007072:Immunoglobulin D; D007136:Immunoglobulins; D011947:Receptors, Antigen, B-Cell; D016201:Receptors, Lymphocyte Homing; D019041:L-Selectin