Innate Immunity: Cytokines and Interferons

Cytokines

Secreted glycoproteins that regulate immune responses by signaling between cells

Chemokines

Chemotactic cytokines that direct migration of leukocytes to tissues; directional signal

CXC Chemokines

Chemokines with one amino acid between the first two conserved cysteines.

CC Chemokines

Chemokines with adjacent conserved cysteines.

CX3C Chemokines

Chemokines with three amino acids between the first two cysteines.

C Chemokines

Chemokines with only one conserved cysteine in the N‑terminus.

Chemokine Receptors

Seven‑transmembrane GPCRs that bind chemokines and signal via G‑proteins. “Composed of 7 transmembrane domains coupled to G proteins…”

CCR1

Constitutively expressed receptor on macrophages; promotes migration and M2 polarization via CCL3.

CCR7

Inducible receptor regulating T‑cell homing and dendritic cell antigen presentation; reduction leads to down regulation and movement of effector cell into the tissue

CXCR1

Neutrophil‑restricted receptor; mediates NET formation in tumors.

CXCR4

Chemokine receptor guiding gut‑homing T cells via CXCL12.

CCL19/CCL21

Homeostatic chemokines directing T‑cell and DC migration in lymphoid organs.

CCL25

Gut‑associated chemokine guiding CCR9⁺ lymphocytes.

CCL28

Chemokine directing IgA‑producing cells to the mammary gland

Antibody secreting cells

Infection sites and secondary lymphoid organs

Interferon

A cell infected by a virus that signals neighboring cells to create a barrier

Type I IFN

Best characterized and produced by most types of cells; systemic response

Type II IFN

Up regulates immuno-response; produced only by certain cells of the immune system

Type III IFN

Recently discovered; functional at mucosal sites against viral infection