Batty P, Hart DP, Platton S. Optimization of pre-analytical heat treatment for inhibitor detection in haemophilia A.
Int J Lab Hematol 2018;
40:561-568. [PMID:
29777571 DOI:
10.1111/ijlh.12862]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 04/16/2018] [Indexed: 11/30/2022]
Abstract
INTRODUCTION
Factor VIII (FVIII) antibody formation is the greatest clinical and laboratory challenge within the haemophilia centre. The Nijmegen-Bethesda assay (NBA) is the gold standard for inhibitor quantification, but affected by pre-analytical variables including a patient's FVIII activity (FVIII:C). Pre-analytical heat treatment (PHT) provides a methodology for inhibitor testing when measurable FVIII:C is present.
METHODS
We evaluated the effect of different PHT conditions (time/temperature) on FVIII:C as well as on potency of inhibitory activity in samples containing FVIII:C (endogenous pooled plasma and exogenous recombinant FVIII (rFL-FVIII) concentrate) or FVIII inhibitor.
RESULTS
PHT of endogenous FVIII at 37°C, 47°C and 52°C resulted in declining measurable FVIII:C at 120 minutes (69%, 57% and 13% of the original FVIII:C, respectively). Incubation at 56°C resulted in FVIII:C ≤ 1IU/dL after 60 minutes for endogenous FVIII and 120 minutes for rFL-FVIII. Incubation at 58°C resulted in FVIII:C < 1IU/dL at 15-30 minutes for endogenous FVIII and at 30-60 minutes for rFL-FVIII. No difference was seen for inhibitor detection following PHT (56°C or 58°C) by NBA or anti-FVIII IgG ELISA.
CONCLUSION
PHT at 58°C for 30 minutes demonstrated consistent reduction in FVIII:C < 1IU/dL without appearing to affect inhibitor detection. Laboratory awareness of differences in thermostability of different sources of FVIII is important when choosing PHT conditions.
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