In Vitro Labelling of Platelets: an Experimental Study on Healthy Asplenic Subjects using Two Different Incubation Media

Abstract

Duplicate platelet survival studies, using autologous platelets labelled in vitro with radioactive sodium chromate, were performed on six young healthy asplenic men. In the first experiment plasma, and in the second a Ringer-citrate-dextrose (RCD) solution (Abrahamsen, 1968), was employed as incubation medium. The uptake of chromate by the platelets was about 2.5 times higher in the RCD compared to the plasma experiments. An identical pattern for the immediate behaviour of infused labelled platelets was observed in the duplicate studies, and the recovery of platelet-bound radioactivity remained stable at the 90% level during 2 h post-infusion. In these experiments the means for platelet mean life span (MLS) were identical, 7.2 +/- 0.5 and 7.2 +/- 0.4 days, respectively. These values slightly, but not significantly, exceeded the mean platelet MLS for a control group consisting of 10 young healthy males (6.9 +/- 0.4 days). The means for platelet production rate (P) at the duplicate studies made on the asplenic subjects were 19 +/- 2 X 10(10) and 21 +/- 2 X 10(10) platelets per day, respectively, and did not differ from the mean for P obtained in the control group (22 +/- 2 X 10(10).

<i>In vitro</i> Labelling of Platelets

“…This is in accord with recent observations made by us on healthy asplenic subjects [7] but at variance with results published by A brahamsen [2]. This author stud ied 12 splenectomized patients with Hodgkin's disease, and employed RCD as the incubation medium.…”

“…However, in those experiments, immediately after infusion, there was a considerable clearance of labelled cells, but after about 15 min they started to reappear in the circulation. On the other hand, this pattern was not observed in a recent study carried out on healthy asplenic subjects in whom the same RCD solution had been em ployed [7]. In those latter experiments, platelet recovery remained stable around the 90% level throughout 2 h after infusion.…”

“…In asplenic subjects, the total number of circulating platelets is obtained from the peripheral platelet count and blood volume. When calculating the total number of circulating platelets in non-splenectomized subjects, a correction for splenic platelet pooling has to be introduced [6,7], The enumeration of platelets was carried out on venous blood using phase mi croscopy [4], The platelet counts reported are the values obtained on day zero.…”

“…After the infusion of la belled platelets, blood samples were obtained at 5, 10, 15, 30, 45, 60, 90 and 120 min. Thereafter, sampling was carried out at 24-hour intervals during a period of 7-9 days [7].…”

“…The entire proce dure has recently been described elsewhere in detail [7]. Platelets were labelled in vitro using 400 f i d of (51Cr) N a2C r0 4.…”