Defective macrophage function in neonates and its impact on unresponsiveness of neonates to polysaccharide antigens.
Neonates do not respond to thymus-independent (TI) antigens (Ag), making them vulnerable to infection with encapsulated bacteria. The antibody (Ab) response of adult and neonatal B cells to TI Ag requires certain cytokines, which are provided by T cells or macrophages (MPhi). Lipopolysaccharide (LPS) failed to induce neonatal MPhi to produce interleukin (IL)-1beta and tumor necrosis factor alpha (TNF-alpha) mRNA and to secrete IL-1beta, IL-12, and TNF-alpha. However, LPS induced neonates to secrete some IL-6 and three- to fivefold more IL-10 than adults. Accordingly, adding adult but not neonatal MPhi could restore the response of purified adult B cells to trinitrophenol (TNP)-LPS, a TI Ag. Increased IL-10 is causally related to decreased IL-1beta and IL-6 production, as IL-10(-/-) neonatal MPhi responded to LPS by secreting more IL-1beta and IL-6 than wild-type (WT) neonatal MPhi. When cultures were supplemented with a neutralizing Ab to IL-10, WT neonatal MPhi secreted increased amounts of IL-6 and allowed neonatal MPhi to promote adult B cells to mount an Ab response against TNP-LPS. Thus, neonates do not respond to TI Ag as a result of the inability of neonatal MPhi to secrete cytokines, such as IL-1beta and IL-6, probably as a result of an excess production of IL-10. This dysregulated cytokine secretion by neonatal MPhi may be a result of a reduction in expression of Toll-like receptor-2 (TLR-2) and TLR-4 and CD14.
Chelvarajan
R L
RL
University of Kentucky, Lexington, KY 40536-0230, USA.
Collins
S M
SM
Doubinskaia
I E
IE
Goes
S
S
Van Willigen
J
J
Flanagan
D
D
De Villiers
W J S
WJ
Bryson
J S
JS
Bondada
S
S
D000818:Animals; D000831:Animals, Newborn / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D004926:Escherichia coli; D005260:Female; D006241:Haptens; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism; D016753:Interleukin-10 / Q000235:genetics / Q000502:physiology; D018664:Interleukin-12 / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000276:immunology*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D006241:Haptens; D007375:Interleukin-1; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; C048761:trinitrophenyl-lipopolysaccharide; D016753:Interleukin-10; D018664:Interleukin-12