[Countermeasures against non-specific reactions in the measurement of beta-glucan in plasma by alkaline treatment, chromogenic automated kinetic assay].
ABSTRACT We investigated the detection of non-specific reactions in the measurement of plasma (1-->3)-beta-D-glucan (beta-glucan) and countermeasures against them using alkaline treatment, chromogenic automated kinetic assay (alkaline-kinetic assay). In this study, we reexamined the values of beta-glucan using the alkaline-kinetic assay with and without laminaran oligosaccharides (LO) as a kind of beta-glucan that blocks the Limulus reaction. The materials for this study were 584 plasma samples in which beta-glucan had been measured. These were taken from 232 patients in Kawasaki Medical School Hospital between January 2002 and March 2002. Non-specific reactions were judged by a calculated value under a LO additive condition. Determination as to whether or not the each time course of the Limulus reaction was influenced by a non-specific reaction was also studied by applying a non-specific reaction index set up independently. Non-specific reactions were recognized in 51.9% of the samples (81/156). The amount of non-specific reaction was 9.9 pg/ml or less in major samples. On the other hand, when the cut off value of the index for detection of non-specific reactions was set at 0.5, the sensitivity was 88.9% and specificity was 73.7%. The positive and negative predictive values were 93.5% and 60.9% respectively. Non-specific reactions can be approximately distinguished by applying the non-specific reaction index. By so doing, unnecessary initiation of anti fugal therapy in response to non-specific reactions can be avoided. Further prospective and radical studies of non-specific reactions in the alkaline-kinetic assay are necessary.