Automated CD61 immunoplatelet analysis of thrombocytopenic samples

Revision of the current decision point for prophylactic platelet transfusio n in thrombocytopenic patients requires the availability of a method that i s able to provide accurate platelet counts to as Low as 1 x 10(9)/l. This s tudy is the first to evaluate the immunoplatelet method (CD61-Imm) of the h aematological analyser Cell-Dyn 4000 in direct comparison with the now cyto metric procedure. Additionally CD61-Imm results were compared with CD4000 o ptical (Plto) counts in the ranges 20-547 x 10(9)/l (n = 127) and 1-35 x 10 (9)/l (n = 107). The immunoplatelet and PIto results were in good agreement between 20 x 10(9)/l and 547 x 10(9)/l, but for samples of < 25 x 10(9)/l the PIto tended to overestimate the counts. We determined the limits of det ection (LD) and quantification (LLQ) for all three methods using standard s tatistical procedures. The LD for the flow cytometric CD41a method was 0.02 x 10(9)/l compared with 0.009 x 10(9)/l and 1.73 x 10(9)/l for the CD61-Im m and Plto methods respectively. The LLQ(CV) = (15%) for the CD41a method w as 1.8 x 10(9)/l compared with 1.6 x 10(9)/l and 18.0 x 10(9)/l for the CD6 1-Imm and Plto procedures. In conclusion, (i) the CD61-Imm method performan ce is at least equivalent to the reference flow cytometric method, and (ii) in severe thrombocytopenia the CD61-Imm count is superior to the Plto coun t.