concanavalin-a and Hyperlipidemias

Effects of experimental hyperlipidemia on apoptosis and proliferation of thymocytes in response to mitogens were studied in CBA and C57Bl/6 mice. The concentrations of cholesterol in the serum and thymocyte membranes increased in both mouse strains. Spontaneous and dexamethasone-induced apoptosis in vitro and the proliferative response to phytohemagglutinin and concanavalin A were enhanced in thymocytes from C57Bl/6 mice and suppressed in cells from CBA mice. These data suggest opposite reactions of thymocyte to increased serum cholesterol concentration in these two strains, associated with stimulation and suppression of cell activity.

Topics: Animals; Apoptosis; Arteriosclerosis; Cell Membrane; Cholesterol; Concanavalin A; Dexamethasone; Diet, Atherogenic; Hyperlipidemias; In Vitro Techniques; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Phytohemagglutinins; Species Specificity; T-Lymphocytes

The effect of hyperlipaemic serum on mitogen-induced T lymphocyte proliferation was investigated with cynomolgus monkeys. The mitogen-induced blastogenesis was remarkably inhibited when either hyperlipaemic or normal monkey lymphocytes were incubated with hyperlipaemic sera. Hyperlipaemic serum also inhibited ConA-induced interleukin 2 (IL-2) production as well as IL-2 receptor (IL-2R) expression of normal monkey lymphocytes. On the other hand, it showed slight inhibition of T-cell proliferation induced by adding recombinant human IL-2 to IL-2R-positive normal monkey lymphocytes. These results indicate that hyperlipaemic serum inhibited an early stage of T-cell autocrine activation pathway including IL-2 production and IL-2R expression.

Topics: Animals; Concanavalin A; Female; Hyperlipidemias; Interleukin-2; Lymphocyte Activation; Macaca fascicularis; Obesity; Receptors, Interleukin-2; Recombinant Proteins; T-Lymphocytes

The implication of HDL as a negative risk factor in cardiovascular disease has focused on the need for an accurate but rapid routine method for determining HDL-cholesterol in human serum. A practical approach is the specific precipitation of apo-B-containing lipoproteins (atherogenic lipoproteins) by Concanavalin A (Con. A), a lectin with high affinity for glycoprotein apo-B. Specificity was assessed by radial immunodiffusion of apoprotein B in whole serum and in Con. A supernates. Double-immunodiffusion of isolated LP-fractions against anti-apo-B and Con. A demonstrated immunochemical identity of Con. A precipitable LP with apo-B-containing LP. Con. A precipitated cholesterol in the d : 1.063-1.21 g/ml fraction when apo-B was present. Complete precipitation of low density cholesterol was demonstrated, using a reconstituted serum sample radiolabelled in the d less than 1.063 g/ml fraction. Treatment of a reconstituted serum sample containing radiolabelled 125I-apo-A-I with Con. A demonstrated precipitation of trace amounts only of apo A-I. Con. A precipitated LP-B cholesterol quantitatively even when serum triglycerides (TG) exceeded 37.7 mmol/l. Clinical application of this method revealed that 73% of the patient population demonstrated apo-B in the d greater than 1.063 g/ml fraction.

Topics: Apolipoproteins; Apolipoproteins B; Chemical Precipitation; Cholesterol; Cholesterol, HDL; Concanavalin A; Humans; Hyperlipidemias; Immunoassay; Lipoproteins; Lipoproteins, HDL; Triglycerides