K phenotyping using a PK-7200 automated analyzer

K (Kell) is one of the most immunogenic of the red blood cell (RBC) antigens. In order to select K- RBC units, we developed K phenotyping on the Olympus PK-7200 equipment to save labor, time, and costs. The Olympus PK-7200 is fully automated equipment used primarily for blood typing and syphilis screening. We tested 3,587 blood donor samples in EDTA using a commercial anti-K serum diluted in HP Hemagen Power Solution(1:40). The equipment was set to prepare a 1.7% RBC suspension in bromelain and to dispense 25 microL of the mixture (diluted serum and HP Hemagen Power Solution) in terraced microplates. After mixing, the microplates were incubated for 1 hour at 30 degrees C. Reading was performed by a C.C.D. camera and the results were automatically transferred to the mainframe computer. We found 185 K+ blood samples and 3,402 K- samples. Four samples, K+ by the PK-7200, were confirmed as K- by tube test. The use of bromelain with the PK-7200 may have caused the falsely positive tests. The Olympus PK-7200, used for K phenotyping, saves labor time and costs. It also reduces handling and thus promotes less contamination risk for laboratory personnel.