The effector pathways recruited for host defense in both the nonimmune and the immune host are specific and generate an array of beneficial functions, but they can also be detrimental to the host if the response is misdirected or excessive. A maladjustment in function of these effector systems so as to contribute to pathologic states of hypersensitivity is not to be viewed as an excessive physiologic response but rather as an involuntary response to an insult extrinsic to the system and of such

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... a nature as to violate the usual mechanisms for maintaining integrity of the host. My growing awareness of the physiologic rather than the pathologic potential of two such systems, namely the mast cell-eosinophil axis, which is situated at portals of possible host penetration by hostile elements, and the alternative complement pathway which distinguishes self from nonself by biochemical rather than immunochemical means, prompts me to emphasize their homeostatic functions.