Clinical experience with transfusion of leukocyte-poor platelet concentrates prepared by filtration with prostacyclin

Repeated transfusions with platelets from randomly selected donors lead to HLA alloimmunization in about 50% of patients due to lymphocyte contamination of platelet concentrates. Attempts to remove the leukocytes from the platelet concentrates by additional centrifugation steps led to substantial loss of platelets. We report a new procedure for removal of almost all leukocytes with excellent platelet recoveries. Single donor concentrates are treated with 50 ng/mL prostacyclin to inactivate the platelets transiently. The concentrates are then passed through a cellulose-acetate filter to remove the leukocytes. In 30 concentrates this treatment reduced the contamination by leukocytes to less than 0.1 million per concentrate with a platelet recovery of 89% +/- 1% (mean +/- SEM). Thirty filtered platelet concentrates transfused to ten thrombocytopenic patients within one hour after filtration were well tolerated and led to corrected count increments of (22.0 +/- 1.1) X 10(6)/mL blood after one hour and normal survival thereafter. In four of five patients these concentrates reduced the bleeding time. We conclude that transient inactivation of platelets by prostacyclin enables optimal removal of leukocytes and may help to reduce alloimmunization during frequent transfusions with platelet concentrates.     

Plasma phospholipid transfer protein activity is related to insulin resistance: impaired acute lowering by insulin in obese Type II diabetic patients

Summary Cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) have important functions in high density lipoprotein (HDL) metabolism. We determined the association of plasma CETP and PLTP activities (measured with exogenous substrate assays) with insulin resistance, plasma triglycerides (TG) and non-esterified fatty acids (NEFA), and assessed the lipid transfer protein response to insulin during a 6–7 h hyperinsulinaemic euglycaemic clamp in non-obese and obese healthy subjects and patients with Type II (non-insulin-dependent) diabetes mellitus (n = 8 per group). Plasma PLTP activity was higher in obese healthy subjects and obese Type II diabetic patients compared with non-obese healthy subjects (p < 0.05 to 0.01) and was correlated with insulin resistance, plasma TG and NEFA (p = 0.02 to < 0.01). In non-obese healthy subjects, insulin decreased plasma TG and increased the HDL cholesteryl ester (CE)/TG ratio (p < 0.01 compared with saline infusion). Plasma PLTP activity fell by 14 % at the end of the clamp (p < 0.01 compared with saline) but CETP activity did not change. The decreases in plasma NEFA, TG and PLTP activity and the rise in HDL CE/TG were smaller in obese Type II diabetic patients than in non-obese healthy subjects (p < 0.01 for all). Baseline HDL CE/TG was negatively correlated with plasma TG (p < 0.001, n = 32) and PLTP activity (p < 0.01) but not with CETP activity. Likewise, the rise in HDL CE/TG during the clamp was related to the fall in plasma TG (p < 0.001) and in PLTP activity (p < 0.02). It is concluded that plasma PLTP, but not CETP, is regulated by insulin in an acute setting. High plasma PLTP activity is associated with insulin resistance in conjunction with altered NEFA and triglyceride metabolism. High plasma TG and PLTP activity have coordinate effects on HDL metabolism. [Diabetologia (1998) 41: 929–934] Received: 12 January 1998 and in revised form: 9 April 1998