Table 1.
Summary of characteristics of different cytokines. Serum samples were taken from 72 healthy subjects including three groups (aged 1–6 years, 7–17 years, and above 18 years). The samples were maintained at 2–8 °C while handling and immediately analyzed utilizing a magnetic bead‐based multiplex immunoassays (Bio‐Plex) (BIO‐RAD Laboratories, Milano, Italy). Cytokine concentrations were measured by Kleiner et al.[ 213 ] Here cytokine concentrations of the adult group (aged above 18 years) is reported. Plasma samples were taken from ten healthy donors. Samples were processed immediately and measured using a Luminex 100 platform (Luminex, Austin, TX) and BioManager software (Bio‐Rad, Hercules, CA). Cytokine concentrations were tested by Jackman et al.[ 208 ] Saliva samples were taken from 262 healthy adolescent girls aged 11, 13, 15, 17 years. Samples were assessed annually for three consecutive years. Salivary cytokines were measured using a 96‐well format multiplex electrochemiluminescence immunoassay manufactured by Meso Scale Discovery (MSD, Gaithersburg, MD). Cytokine concentrations were measured by Riis et al.[ 212 ] Here, saliva concentrations collected in the first year is reported. Tear samples were taken from six female and three male healthy volunteers (age range 25–51). All tear samples were obtained approximately at the same time of the day (16:00–19:00 h) and from the right eye first and then from left eye and were kept cold during collection and stored at −80 °C until assayed. Cytokine levels were determined by multiplex bead analysis in a Luminex IS‐100 instrument (Luminex Corporation, Austin, TX, USA). Cytokine concentrations were measured by Carreno et al.[ 209 ] Stool samples were taken from healthy adults aged 40–65. These samples were collected in specimen containers and placed into plastic bags, surrounded by frozen gel packs, delivered to the center and stored at −80 °C. Stool cytokines were measured by ELISA. Cytokine concentrations were measured by Vanegas et al.[ 216 ] Here, cytokine levels collected from participants eating refined‐grain for 2 weeks is reported
| Concentrations [pg mL−1] in different in vitro body fluids | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Cytokines | Cytokine type | Cell sources | Half life | Biological functions | Serum | Plasma | Saliva | Tears | Stool | References |
| IL‐1β | Pro‐inflammatory | Monocytes/macrophages | 21 min | Principal mediator of the systemic effects of IL‐1; it affects IL‐6‐induced gene expression | – | 1.5 ± 1.2 | 1.5–5.3 × 102 | 102 ± 2.8 | – | [ 207 , 208 , 209 , 210 , 211 , 212 ] |
| IL‐6 | Pro‐ and anti‐inflammatory | B and T cells, monocytes, fibroblasts, endothelial cells, and some tumor cells | 15.5 h |
Inducer of the acute‐phase response as well as specific cellular and humoral immune responses. Inhibition of TNF and IL‐1 production by macrophages |
8.5–14 | 22 ± 8.6 | 0–27 | 1.3 × 102 ± 12 | 0.3 ± 0.1 | [ 207 , 208 , 209 , 212 , 213 , 214 , 215 , 216 ] |
| IL‐8 | Pro‐inflammatory | Monocytes, macrophages, endothelial cells, epithelial cells, hepatocytes, chondrocytes, and tumor cells | 24 min | Pro‐inflammatory mediators that orchestrate the recruitment of leukocytes to sites of inflammation | 24–36 | 9.4 ± 3.7 | 0.4–3.2 × 102 | – | – | [ 208 , 211 , 212 , 213 , 214 ] |
| IL‐12 | Pro‐inflammatory | Phagocytic cells, microglial and dendritic cells | – | Th cell differentiation, TNF‐α, IFN‐γ synthesis | 20–56 | 1.2 × 102 ± 8.6 | 0–7.6 | 47 | – | [ 90 , 208 , 209 , 212 , 213 ] |
| TNF‐α | Pro‐inflammatory | Macrophages, mast cells, NK cells, VSMCs, T‐ and B‐cells | 18.2 min | Pro‐inflammatory, neutrophil activation, bone resorption, anticoagulant, tumor necrosis, activate and increase permeability, stimulate adhesion molecules | 28–38 | 5.9 ± 0.4 | 0–5.8 | 48 ± 3.3 | 1.8 ± 0.3 | [ 6 , 91 , 207 , 208 , 209 , 212 , 213 , 216 ] |
| IFN‐γ | Pro‐inflammatory | Macrophages, Th1 cells, Tc cells, B‐cells, Natural killer (NK) cells, VSMCs | – | Pro‐inflammatory, promotes Th1 immune responses/secretion of Th1‐associated cytokines, inhibits ECM synthesis by SMC MHC I expression | (1.2–1.6) × 102 | 7 ± 2.5 | 0–7 | 42 ± 3.6 | 0.4 ± 0.2 | [ 6 , 208 , 209 , 212 , 213 , 216 ] |
| IL‐1RA | Anti‐inflammatory | Monocytes/macrophages, dendritic cells | 4–6 h | Inhibition of IL‐1α‐ and IL‐1β‐mediated cellular activation at the IL‐1 cellular receptor level | (1–1.7) × 102 | 50 ± 21 | – | (3.9 ± 0.9) × 103 | – | [ 67 , 208 , 209 , 213 , 217 ] |
| IL‐4 | Anti‐inflammatory | T cells (Th2), mast cells, B cells, stromal cells | 20 min | Promotes Th2 lymphocyte development; inhibition of LPS‐induced proinflammatory cytokine synthesis | 6.9–8.1 | (2.3 ± 0.5) × 102 | – | 21 ± 1.6 | – | [ 67 , 207 , 208 , 209 , 213 , 218 ] |
| IL‐10 | Anti‐inflammatory | Monocytes/macrophages, T cells (Th2), B cells | – | Inhibition of monocyte/macrophage and neutrophil cytokine production and inhibition of Th1‐type lymphocyte responses | 8.5–17 | 38 ± 2.1 | 0–10 | 37 ± 0.9 | – | [ 67 , 208 , 209 , 212 , 213 ] |
| IL‐11 | Anti‐inflammatory | Stromal cells, fibroblasts | – | Inhibits proinflammatory cytokine response by monocytes/macrophages and promotes Th2 lymphocyte response | – | – | – | – | – | [ 67 ] |
| IL‐13 | Anti‐inflammatory | T cells (Th2) | – | Shares homology with IL‐4 and shares the IL‐4 receptor; attenuation of monocyte/macrophage function | 11–18 | (1.1 ± 0.2) × 102 | – | 47 ± 3.2 | – | [ 67 , 208 , 209 , 213 ] |