Inflammation-induced changes in rabbit CRP and plasma lipoproteins.

Inflammation is accompanied by changes in the plasma concentrations of "acute phase reactants" including the C-reactive proteins of man and other species. Previous results in our laboratory showed that CRP in rabbit acute phase serum may circulate in association with very low density lipoproteins (VLDL), which influence both the apparent m.w. and electrophoretic mobility of CRP. We now show that the ability of VLDL to interact with CRP varies with time during the acute phase response. Before the induction of inflammation, the factor(s) responsible for the beta-mobility of CRP is present at low levels in the VLDL. During the first 24 hr of the acute phase response, the activity can no longer be demonstrated in the VLDL fraction. By 36 to 48 hr after inflammatory stimulation, a significantly increased level of this factor(s) is measurable in VLDL. Furthermore, during the acute phase response, the alpha-lipoproteins decrease, and the beta- and pre-beta lipoproteins increase. The increase in beta- and pre-beta-lipoproteins is due to an accumulation of VLDL isolated at d less than 1.006 g/ml. These changes are accompanied by marked hypertriglyceridemia and a significant increase in phosphocholine-containing phospholipids. A non-CRP apoprotein present in low amounts in VLDL from normal rabbit plasma appears to increase in VLDL as inflammation progresses. This VLDL apoprotein increases in response to multiple acute phase stimuli and may be a newly recognized acute phase reactant in the rabbit.