Acute phase response, mechanism

Decreased monocyte production of TNF also has been reported in SLE (Y9), as has decreased IL-6 production in patients with chronic lymphocytic leukemia, whereas Yorston et al. (Y5) showed that patients with recurrent iritis are progressively less likely to show acute phase responses with increasing numbers of previous attacks. In some conditions the acute phase response mechanisms may become refractory to certain stimuli or it may be that a greater degree of stimulation is required in chronic disease. Defective host response to tissue damage or injury could therefore enhance or perpetuate inflammation. 

Bacterial infections elicit a series of acute-phase responses which include central nervous system effects such as changes in body temperature and increased slow-wave sleep. Dead bacteria [54] and murein preparations [55] as well as other bacterial cell-wall products induce similar responses. Intravenous injections of rabbits with suspensions of pseudomurein from Methanobacterium thermoautotrophicum also alter sleep and brain temperature. The mechanisms responsible for these somnogenic and pyrogenic effects are unknown [56]. It has been demonstrated that in a rat arthritis model, intra-articular injection of high doses of pseudomurein-polysaccharide fragments from Methanobacterium formicicum caused an acute inflammation [57]. 

The Acute Phase Response (APR) is a complex phenomenon involving many biochemical and functional mechanisms [1]. A recent review published in New England Journal of Medicine [2] gave the following definition ... 

The Acute-Phase Response, an important pathophysiologic phenomenon, replaces the normal homeostatic mechanisms with new set points that are presumably contributing to defensive or adaptive capabilities. The functions of these changes are highly variable and diverse some participate in initiating or sustaining the inflammatory process, others modulate it, and still others have adaptive roles... 

W27. Whicher, J. T., Westacott, C. I., and Dieppe, P. A. Defective acute phase response in systemic sclerosis Disease mechanisms and consequences. Protides Biol. Fluids 34, 605-609 (1986). 

---