Implementation of a proficiency testing program for Lyme disease in New York State.

Nine proficiency test events for Lyme disease (Borrelia burgdorferi) antibody were carried out from October 1988 to January 1992 by the New York State Department of Health, Albany, Overall sensitivity for the 846 participants averaged 95.4%, with varying sensitivities of 98.7% for users (71 laboratories) of immunofluorescence assays, 97.4% for users (144 laboratories) of solid-phase fluorescence immunoassays, and 94.6% for users (631 laboratories) of enzyme immunoassays. Thirty percent of the enzyme immunoassay laboratories tested at greater than or equal to 98.4% sensitivity by the DiaMedix test kit (DiaMedix Corp, Miami, Fla) and MarDx test kit (MarDx Diagnostics Inc, Scotch Plains, NJ), while 7% tested at less than or equal to 83% by the Access test kit (Access Medical Systems Inc, Branford, Conn) and the Cambridge BioScience test kit (Cambridge BioScience, Worcester, Mass). Overall specificity was 98.8%, with specificities greater than 99% for both solid-phase fluorescence immunoassay and enzyme immunoassay users and 92.9% for immunofluorescence assay users. Cross-reactivity with Treponema pallidum antibody was high for the Hillcrest (Hillcrest Biologicals, Cypress, Calif) (30%) and Wampole (Wampole Laboratories, Cranbury, NJ) (25%) immunofluorescence assay test kit users and for the MarDx (30%) and 3M (3M Diagnostics Systems Inc, Santa Clara, Calif) (24%) enzyme immunoassay test kit users. Laboratories that tested by the Wampole immunofluorescence assay test kit had also high cross-reactivity (25%) against heterophile antibody.

Improved procedure for platelet freezing.

Platelets frozen in glycerol-glucose frequently aggregated on thawing or reconstitution. This has been eliminated by using a nonplasma diluent (pH 6.5) and a new freezing bag. The results were improved platelet 14C-serotonin uptake and readily demonstrable aggregation to ADP, epinephrine, collagen and thrombin. 14C-serotonin uptake was at maximum when platelets were frozen at thrombocrits of up to 15%. Hemostatic effectiveness was demonstrated in a severely thrombocytopenic patient with acute myelogenous leukemia in relapse, who was supported entirely with two autologous frozen platelet transfusions for the 13 days before bone marrow activity resumed.

A simplified method for freezing human blood platelets in glycerol-glucose using a statically controlled cooling rate device.

An inexpensive, statically controlled cooling rate device consisting of a cassette of aluminum plates and cardboard insulation in a plastic bag was used to freeze platelets in liquid nitrogen with glycerol-glucose as cryoprotectant. Depending on the thermocouple location, the cooling rate in the freezing bag varied between 22.1 and 38.6 C per minute, averaging 33.6 +/- 1.1 C per minute at the center. The post-thaw recovery of platelets frozen with this device and reconstituted in plasma averaged 88.6 +/- 11.7 per cent, compared to 86.1 +/- 9.9 per cent for nonfrozen, but otherwise identically processed platelets. 14C Serotonin uptake after 0.5-hour incubation was 95.9 +/- 1.9 per cent for fresh platelets in platelet-rich plasma, 92.7 +/- 4.4 per cent for nonfrozen processed platelets, and 81.4 +/- 11.8 per cent for frozen platelets, increasing to 85.9 +/- 7.7 per cent after one-hour incubation.