[Effect of hyperlipemia on mitogen-induced blastogenesis in lymphocytes isolated from the rat spleen].

Lipoproteins suppress several immune functions (mitogen-induced lymphoblast transformation, macrophage functions). Low density lipoprotein (LDL) is responsible for most of these effects. Diet may cause an elevation in LDL level.

Immunomodulating effect of low density lipoprotein on human monocytes.

Low density lipoprotein (LDL) isolated from sera of healthy volunteers in 50 micrograms protein/ml concentration induced an early adenylate cyclase activation in human monocytes followed by elevation of cGMP level. In addition, a rapid 45Ca2+ influx was also detected on addition of 25-100 micrograms protein/ml concentrations. The monocyte activating effect of LDL under in vitro circumstances was characterized by an enhanced O2 consumption, H2O2 generation and by the increased release of lysosomal enzymes such as beta-glucuronidase and elastase like protease (ELP).

Autoimmunity and normal immune functions in aged humans.

The high frequency of ANA, A-LDL and RF in advanced age suggests that AABs are present in the majority of aged subjects. CIC incidence determined by three methods is far below AAB incidence; only the Clq solubility test suggests an increased CIC incidence in aged as compared to young subjects. Simultaneous occurrence of AABs of different specificities or CIC determined by two or three methods is rare and both AAB and CIC levels are usually low.

Occurrence of anti-low density lipoprotein antibodies and circulating immune complexes in aged subjects.

The incidence of circulating immune complexes, anti-low density lipoprotein (LDL) autoantibodies and the anti-LDL activity of immune complexes was studied in healthy young and aged controls and in patients with vascular diseases. Circulating immune complexes (CIC) frequently occurred both in the young or old patient groups and in the aged healthy control groups, whereas they could not be found in the young controls. Marked differences were found in the incidence of anti-LDL antibodies between the groups tested.