title: Antigen presentation for T cell interleukin-2 secretion is a late acquisition of neonatal B cells.
abstract: The ability of B lymphocytes to process and present antigen to helper T cells is essential to initiate T cell-B cell interactions in humoral immune responses. Here we describe the developmental acquisition of the antigen-presenting function of B cells as measured by the ability of B cells to stimulate a T cell hybrid to interleukin (IL)-2 secretion. Neonatal splenic B cells are not adult-like in their ability to process and present the model protein antigen pigeon cytochrome (Pc), which enters the B cell through fluid-phase pinocytosis, until 21 to 28 days of life. The ability of neonatal B cells to process and present antigen which enters the cell bound to surface Ig is not adult-like until 28 days of age. When neonatal B cells acquire antigen-presenting cell (APC) function, surface IgM facilitates antigen processing. The delayed acquisition of APC function cannot be accounted for solely by a deficiency in major histocompatibility complex MHC class II, ICAM-1, or LFA-1 as neonatal B cells express adult levels of these molecules by 7-14 days after birth. Moreover, the ability of neonatal B cells to present a peptide fragment of Pc which does not require processing is adult like by day 14. Furthermore, neonatal B cells are capable of binding, internalizing and degrading radiolabeled antigen, suggesting a more subtle level of regulation. In contrast to neonatal B cells, immature B cells in the adult bone marrow and adult B cells undergoing antigen-driven differentiation to memory B cells, as defined by the loss of the J11D marker, are competent to process and present antigen resulting in T cell IL-2 secretion. Thus, developing B cell subpopulations in the adult and in the neonate can be distinguished. Only neonatal B cells are deficient in their ability to stimulate T cells to IL-2 production.
authors.affiliation: Department of Biochemistry, Northwestern University, Evanston, IL 60208-3500.
authors.forename: J F
authors.initials: JF
authors.lastname: Morris
authors.forename: J T
authors.initials: JT
authors.lastname: Hoyer
authors.forename: S K
authors.initials: SK
authors.lastname: Pierce
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000276:immunology*; D000938:Antigen-Presenting Cells / Q000502:physiology*; D001402:B-Lymphocytes / Q000502:physiology*; D005260:Female; D007156:Immunologic Memory; D007376:Interleukin-2 / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D013601:T-Lymphocytes / Q000378:metabolism*
chemical_list: D007376:Interleukin-2; D011947:Receptors, Antigen, B-Cell