Immune System & Aging
22 terms
- B-cell senescence
B-cell senescence encompasses age-related changes in B-cell development, composition, and function that collectively impair humoral immunity. A hallmark is the accumulation of…
- CD4/CD8 ratio
The CD4/CD8 ratio is the proportion of CD4+ helper T cells to CD8+ cytotoxic T cells in peripheral blood, with a healthy reference range typically cited as approximately 1.5–2.5.…
- Clonal hematopoiesis (CHIP)
Clonal hematopoiesis of indeterminate potential (CHIP) refers to the somatic expansion of a hematopoietic stem cell clone carrying a driver mutation — most commonly in DNMT3A,…
- CMV (Cytomegalovirus)
Cytomegalovirus is a ubiquitous beta-herpesvirus that establishes lifelong latency after primary infection, with seroprevalence ranging from roughly 40–70% in high-income…
- Complement system
The complement system is a network of more than 30 plasma and membrane-bound proteins that constitute an effector arm of innate immunity, activated through three converging…
- Dendritic cells
Dendritic cells (DCs) are bone-marrow-derived antigen-presenting cells bridging innate and adaptive immunity. Two main subsets circulate in blood: plasmacytoid DCs (pDCs) detect…
- IL-10 / anti-inflammatory cytokines
Interleukin-10 is a pleiotropic anti-inflammatory cytokine produced primarily by macrophages, T regulatory cells, and B cells that restrains pro-inflammatory signalling by…
- IL-1β (Interleukin-1 beta)
IL-1β (Interleukin-1 beta) is a pro-inflammatory cytokine produced by monocytes and macrophages, mediating both acute inflammation and inflammaging — the sterile, low-grade…
- Immunosenescence
Immunosenescence is the age-related remodelling of the immune system characterised by a decline in naive lymphocyte output from the thymus and bone marrow, clonal expansion of…
- M1/M2 macrophage polarization
The M1/M2 framework describes macrophage activation states at two functional extremes: M1 (classically activated) macrophages, induced by IFN-γ and LPS, produce pro-inflammatory…
- Naive vs. memory T cells
Naive T cells are antigen-inexperienced lymphocytes that continuously recirculate through secondary lymphoid organs awaiting their cognate antigen; they are generated in the…
- NK cells (Natural Killer cells)
Natural Killer cells are innate lymphoid cells that eliminate virus-infected and malignant cells without prior antigen sensitisation, governed by a balance of activating…
- Plasma cells
Plasma cells are terminally differentiated B cells that have lost expression of B-cell surface markers including BCR-associated CD79 and gained high-level expression of the…
- Specialized pro-resolving mediators (SPMs)
Specialized pro-resolving mediators (SPMs) are endogenous bioactive lipids from polyunsaturated fatty acids: lipoxins arise from arachidonic acid (omega-6), while resolvins,…
- T-cell exhaustion
T-cell exhaustion is a hypofunctional state acquired by antigen-specific T lymphocytes — primarily CD8+ cytotoxic T cells — under persistent antigen exposure, such as chronic…
- Thymic involution
Thymic involution is the progressive replacement of thymic epithelial space by adipose tissue that begins in early childhood and accelerates at puberty, reducing the organ's…
- TNF-α (Tumour Necrosis Factor alpha)
Tumour Necrosis Factor alpha is a pleiotropic pro-inflammatory cytokine produced predominantly by macrophages and monocytes in response to infection or tissue damage, signalling…
- Toll-like receptors (TLRs)
Toll-like receptors (TLRs) are ten surface and endosomal pattern recognition receptors forming a primary sensing layer of innate immunity. Cell-surface TLRs (TLR1, TLR2, TLR4,…
- Trained immunity
Trained immunity, a concept developed primarily by Mihai Netea and colleagues, refers to the capacity of innate immune cells — principally monocytes, macrophages, and NK cells —…
- Tregs (T regulatory cells)
T regulatory cells are a specialised CD4+ T-cell subset defined by expression of the transcription factor FOXP3 that suppresses excessive immune responses and maintains…
- Type I interferons (IFN-α/β)
Type I interferons — primarily IFN-α (multiple subtypes) and IFN-β — are cytokines secreted by virtually all nucleated cells in response to viral nucleic acids detected by innate…
- Vaccine response in aging
The vaccine response deteriorates with aging due to multiple converging immunological deficits: reduced naive T- and B-cell diversity, impaired germinal centre reactions,…