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The Innate Immune Response

What is the Innate Immune System?

Innate immunity provides a general immune response, meaning it is not specific to a particular pathogen; any foreign body or non-self molecule is a target.

The innate immune system includes physical barriers such as the skin and other epithelial surfaces that act as the first line of defense. However, when epithelial barriers are breached, other components of the innate immune response detect pathogens via germ line-encoded pattern recognition receptors, leading to a rapid immune response (within minutes to hours).

These pattern recognition receptors are often directed against cell surface and cell wall components of microorganisms, but bacterial DNA containing unmethylated CpG motifs also induce an innate immune response.

Cells of the Innate Immune System

During hematopoiesis, the common myeloid progenitor (CMP) cell gives rise to the myeloid lineage which includes most of the component cells of the innate immune response.

CMP cells are a precursor to monocytes, which differentiate into macrophages and dendritic cells, and also cells of the granulocyte lineage, which includes mast cells, neutrophils, eosinophils and basophils. In contrast, cytotoxic natural killer (NK) cells are a component of the innate immune response derived from common lymphocyte progenitor (CLP) cells

These immune cells can be distinguished by a variety of phenotypic markers.

Innate Immune Signaling

Most cell types not specific to the immune system can harbor intrinsic innate immune functions in the form of cytoplasmic receptors and signaling and effector molecules. Signaling pathways active in the innate immune response include:

  • STING signaling pathway, which induces type I interferon production when cytosolic DNA sensors detect infection by intracellular pathogens, such as viruses, mycobacteria and intracellular parasites.
  • Toll-like receptor (TLR) signaling, which activates immune cell responses when cell surface TLRs detect distinct pathogen-associated molecular patterns.
  • Inflammasome mediated activation of Caspase-1 inflammatory responses when cytosolic pattern recognition receptors on inflammasomes detect danger signals from pathogenic microbes and host-derived signals of cellular distress.

CST is the leader in the production of validated antibodies for the characterization of intracellular signaling pathways and offers numerous antibodies directed against components of the STING, TLR, and inflammasome pathways.