The neurohormonal arm of the stress response is well defined. Less is known about the inflammatory arm mediated primarily by cytokines. Which of the following statement(s) is/are true concerning this arm of the surgical stress response?

a. Cytokines primarily work locally via direct cell-to-cell communication

d. Cytokine release may stimulate the release of other cytokines leading to an important cascade of events

Cytokines, which are produced at the site of injury by endothelial cells and by diverse immune cells throughout the body, also occupy a pivotal position in the stress response. Cytokines differ from classic endocrine hormones in that they are produced by a variety of cell types and in that they have the capacity to exert their tissue effects locally via direct cell-to-cell communications in a paracrine and/or autocrine fashion. Cytokines can stimulate the production of other cytokines, leading to important cascades which both amplify and diversify the effects of the proximal cytokine. Occasionally, when in excess, cytokines act as hormones and “spill over” into the systemic circulation and become detectable in the bloodstream.