Decreased TNF-alpha synthesis by macrophages restricts cutaneous immunosurveillance by memory CD4+ T cells during aging.
Immunity declines during aging, however the mechanisms involved in this decline are not known. In this study, we show that cutaneous delayed type hypersensitivity (DTH) responses to recall antigens are significantly decreased in older individuals. However, this is not related to CC chemokine receptor 4, cutaneous lymphocyte-associated antigen, or CD11a expression by CD4(+) T cells or their physical capacity for migration. Instead, there is defective activation of dermal blood vessels in older subject that results from decreased TNF-alpha secretion by macrophages. This prevents memory T cell entry into the skin after antigen challenge. However, isolated cutaneous macrophages from these subjects can be induced to secrete TNF-alpha after stimulation with Toll-like receptor (TLR) 1/2 or TLR 4 ligands in vitro, indicating that the defect is reversible. The decreased conditioning of tissue microenvironments by macrophage-derived cytokines may therefore lead to defective immunosurveillance by memory T cells. This may be a predisposing factor for the development of malignancy and infection in the skin during aging.
Agius
Elaine
E
Department of Immunology, Division of Infection and Immunity, University College London, London, W1T 4JF, England, UK.
Lacy
Katie E
KE
Vukmanovic-Stejic
Milica
M
Jagger
Ann L
AL
Papageorgiou
Anna-Pia
AP
Hall
Sue
S
Reed
John R
JR
Curnow
S John
SJ
Fuentes-Duculan
Judilyn
J
Buckley
Christopher D
CD
Salmon
Mike
M
Taams
Leonie S
LS
Krueger
James
J
Greenwood
John
J
Klein
Nigel
N
Rustin
Malcolm H A
MH
Akbar
Arne N
AN
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000276:immunology*; D007150:Immunohistochemistry; D007157:Immunologic Surveillance / Q000276:immunology*; D008264:Macrophages / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D012867:Skin / Q000276:immunology*; D018709:Statistics, Nonparametric; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000378:metabolism
D014409:Tumor Necrosis Factor-alpha