Figure 6.2.

Exocytosed mediators from activated MCs. The MCs that reside in the skin and other connective tissues contain numerous receptors on their plasma membranes that they use in innate (e.g., complement and TLRs) and acquired (e.g., FcεRI and FcγRIII) immunity. MCs also can recognize and respond to numerous endogenous factors like ATP that are often increased in wounded skin, as well as epitopes recognized by naturally occurring IgM autoantibodies. In the early phase, activated MCs rapidly exocytose the contents of their secretory granules and increase their expression of varied lipid mediators. In the late phase, the activated cell markedly increases the expression of numerous cytokines and chemokines. MCs also have inhibitory receptors that dampen cellular activation.