Unlike the receptors that mediate adaptive immunity, the receptors of the innate immunity are typically not clonally distributed; a given set of receptors will be present on all the cells of the same cell type. The binding of pathogens by these receptors gives rise to very rapid responses, which are put into effect without the delay imposed by the clonal expansion of cells needed in the adaptive immune response.
The innate immunity related cells including: NK cells, mast cells, monocytes and dendritic cells, and function within the immune system by identifying and eliminating pathogens that might cause infection. The innate immunity recognizes such pathogens by means of receptors that bind features of these regular patterns; these receptors are sometimes known as pattern-recognition molecules. The innate immunity receptors that recognize pathogens also have an important role in signaling for the induced responses responsible for local inflammation, the recruitment of new effector cells, the containment of local infection, and the initiation of an adaptive immune response.