Effects of immune complexes on plasma triglycerides in rabbits.

The effect of immune complexes on plasma lipids, especially triglycerides (TG) was studied in rabbits. After a single intravenous dose of bovine serum albumin (BSA), serological aberrations suggestive of immune complexes appeared around the 14th day. Changes in the plasma TG or cholesterol values were not observed within a follow-up period of 4 weeks. However, reimmunization with a second dose of BSA 2 months later led to a significant decrease in plasma TG (P less than 0.01). In fat tolerance tests TG emulsion was given intravenously to rabbits immunized 14 days earlier with BSA. The elimination curve of exogenous TG (followed for 100 men) was in its first phase exponential and in it second phase linear in all experimental groups. The significance of the second phase, however, has to be interpreted with some caution because of the possible recirculation of TG into the blood stream. In the rabbits immunized with one dose of BSA the fractional removal rate of TG did not differ from that of the controls. However, in the rabbits reimmunized with a second dose of BSA 2 months later the fractional removal rate of TG was greater than in the controls (P less than 0.01). It was concluded that immune complex lesions under certain circumstances may affect the TG metabolism. The mechanism concerned may be increased permeability of the injured vascular endothelial cells, possibly through the increased release of lipoprotein lipase (LPL).