Table 1.

Characteristics of monocytes/macrophages-derived cytokines.

Cytokine	Structure	Size molecular weight	Receptors	Cell targets	Major functions	Disease association
IL-1α, IL-1β	Heterodimer	17 kd	IL-1RI, IL-1RII	T cells, fibroblasts, epithelial and endothelial cells	Induction of Proinflammatory proteins, hematopoiesis, differentiation of Th17 cells	Wide range of autoimmune and inflammatory diseases: AD, RA, IBD, psoriasis
IL-3	Monomer	15 kd	IL-3Rα + βc (CD131)	Erythroid progenitors, Granulocyte macrophages progenitors, CD34+ progenitor cells, basophils, eosinophils	Hematopoietic growth factor, activation of basophils and eosinophils	Role in allergic diseases for example, AD, different types of cancers, lymphocytic and acute myeloid leukemias
IL-6	Homodimer	19–26 kd	IL-6R, (sIL-6R) gp130	Hepatocytes, leukocytes, T cells, B cells, hemopoietic cells	Liver: synthesis of acute phase proteins; leukocytes: trafficking, activation; T cell: differentiation, activation, survival; B cell: differentiation, production of IgG, IgM, IgA hematopoiesis	Autoimmune disease, chronic inflammatory diseases for example, AD, B-cell malignancy, SLE, Castleman's disease, plasmacytoma/multiple myeloma
IL-7	Monomer	25 kd	IL-7R and sIL-7R	B, T, and NK cells	Proliferation of pre-B and pro-B cells (mice), megakaryocytes maturation, VDJ recombinations, naive T-cell survival, synthesis induction of inflammatory mediators in monocytes	Allergy/autoimmunity and psoriasis
IL-8 (CXCL8)	Homodimer	16 kd	CXCR1 and CXCR2	Neutrophils, NK cells, T cells, basophils, eosinophils, endothelial cells	Chemoattractant for neutrophils, NK cells, T cells, basophils, eosinophils; mobilization of hematopoieticstem cells; angiogenesis	Increased levels during inflammatory diseases (e.g., AD, RA, psoriasis, bacterial and viral infections)
IL-10	Homodimer	20.5 kd, predicted size of precursor protein; 18.6 kd, predicted size mature protein, monomer	IL-10R1/IL-10R2 complex	Macrophages, monocytes, T cells, B cells, NK cells, mast cells, DC and granulocytes	Immune suppression	Cancer, autoimmunity, allergy (e.g., AD)
IL-12 (p35/p40)	Heterodimer	IL-12a p35, 35 kd; IL12b p40, 40 kd	IL-12Rb1 and IL-12Rb2	T cells (Th1 cells), NK cells	Induce Th1-cell differentiation and cytotoxicity	Chronic inflammation (e.g., AD), impaired Th1 response with higher susceptibility to intracellular pathogens, use as anticancer agent
IL-15	Monomer	14-15 kd	IL-15R	T, NK, and NKT cells T-cell activation	Proliferation and activation of NK cells, differentiation of γ/Δ T cells, suppression of IL-2 induced AICD of T cells, homeostasis of CD8+ memory, NK and NKT cells, enhancement of Th2 differentiation and suppression of allergic rhinitis	Autoimmune and inflammatory diseases
IL-16	Homotetramer	56 kd	CD4	T cells, monocytes, macrophages, eosinophils	Chemotaxis, modulation of T-cell response	Increased during various inflammatory and infectious diseases including atopic eczema, allergic asthma, Crohn's disease, RA, hepatitis C infection, tuberculosis; inhibits HIV infection
IL-18	Heterodimer	22.3 kd	IL-18R	Variety of cells, T cells, NK cells, macrophages, epithelial cells, chondrocytes	Induction of IFN-γ in presence of IL-12, enhances NK cell cytotoxicity, promoting Th1 or Th2-cell responses depending cytokine milieu	Autoimmune diseases or inflammatory disorders, AD, RA, psoriasis, MS, type I diabetes
IL-19	Monomer	20.5 kd predicted size of precursor; 17 kd, predicted size of mature protein; 35–40 kd, found in transfected cells, glycosylated	IL20R1/IL-20R2	Keratinocytes	Unknown	Psoriasis
IL-20	Monomer	20 kd predicted size of precursor; 17.5 kd, predicted size of mature protein	IL-20R1/IL-20R2 and IL-22R1/IL-20R2	Keratinocytes, monocytes	Role in skin biology	Psoriasis, RA, atherosclerosis
IL-23 (p191p40)	Heterodimer	IL-12b p40, 40 kd; IL-23 p19, 19 kd	IL-12Rb1 and IL-23R	T cells (TH17 cells) and macrophages	Stimulate production of proinflammatory IL-17 and promote memory T-cell proliferation	Susceptibility to extracellular pathogens, exacerbate organ specific autoimmune inflammation, chronic inflammatory diseases (psoriasis, AD)
IL-24	Homodimer and monomer	23.8 kd, predicted size of unprocessed precursor; 18 kd, unglycosylated mature protein; 35 kd, observed size of secreted IL-24, glycosylated	IL20R1/IL-20R2 and IL-22R1/IL-20R2	Keratinocytes, cancer cells	Tumor suppression	Melanoma, psoriasis
IL-27 (p281EBI3)	Heterodimer	IL-27a p28, 28 kd; IL-27b EBI3, 25.4 kd	WSX-1 and gp130	T cells, NK cells	Induction of Tbet promoting Th1-cell differentiation, inhibition of Th17-cell response via STAT1	Immune pathology because of uncontrolled inflammatory response: for example, in psoriasis or in epidermal compartment of patients with eczema
IL-32	Unknown	14.9–26.6 kd	Unknown	Macrophages, DCs, T cells, PBMCs, monocytes	Induction of TNF-α, IL-8, and IL-6, apoptosis	AD, RA, IBD, autoimmune disease
IL-37	Unknown	17–24 kd	IL-18Ra?	Intracellular mechanism manner and DC	Suppression of proinflammatory cytokines and inhibition of DC activation	RA
TNF-α	Homotrimer	26 kd transmembrane and a 17 kd secreted form	TNF-R1 and TNF-R2	Both receptors are virtually on all cell types except for the red blood cells, but TNFR1 is more ubiquitous, and TNFR2 is often more abundant on endothelial cells and cells of hematopoietic lineage	Regulation of immune cells: induce fever, apoptotic cell death, (through IL-1 and L-6 production, inhibit tumorigenesis and viral replication, recruiting macrophage and neutrophils to a site of infection	Chronic inflammation (AD, psoriasis, RA, IBD, COPD), Alzheimer's disease, cancer

AD:  atopic dermatitis; AICD: activation-induced cell death; COPD: chronic obstructive pulmonary disease; IBD: inflammatory bowel disease; Ig:  immunoglobulin; kd: kilo Dalton; NK:  natural killer; RA: rheumatoid arthritis; SLE:  systemic lupus erythematosus; sIL-6R: soluble interleukin-6 receptor; Th: T helper.