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BACKGROUND AND OBJECTIVES Accurate determination of residual leucocytes [white blood cells (WBC)] in blood components is of high clinical importance. To date, several labour-intensive, time-consuming or expensive techniques have been used for this purpose. MATERIALS AND METHODS A method for the determination of residual WBC is described using a novel low-cost flow-cytometric cell counter and analyser (CCA). The DNA in WBC was stained using 4'-6-diamidino-2-phenylindole (DAPI) and WBC were automatically analysed by true volumetric counting of 200-microl samples (prepared from a 20-microl undiluted sample). RESULTS Dilution experiments over a range of 0.5-50 WBC/microl showed a linearity of r = 0.998. The detection limit of this method was 0.83 WBC/microl of red blood cell concentrate (RCC) and 0.67 WBC/microl of platelet concentrate (PC), with an accuracy of 95.5%. CONCLUSION Residual WBC (< 1 WBC/microl) can be accurately counted using the CCA within 2 min and at a total cost of less than euro 1 per sample.

Background: Psoriasis is a chronic inflammatory skin disease. Reactive oxygen species are thought to play a critical role in inflammation and are scavenged by antioxidants. Objective: We wanted to know whether the total antioxidative capacity or single antioxidative components in sera from psoriasis patients are decreased. Material and Methods: Well-known antioxidants of the serum were measured using commercial kits or determined by HPLC in the sera of 33 inpatients with severe psoriasis and in 36 healthy control persons. The total antioxidative capacity was measured using the ability of endogenous antioxidants to scavenge the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation. Results: Several single antioxidative components were slightly elevated when considered groupwise, namely tocopherol (p = 0.001), bilirubin (p = 0.001) and urate which was increased over controls by about 33% (p= 0.01). Other parameters such as total protein and thiol content and ascorbic acid did not differ from controls. Conclusion: To our surprise the total antioxidative activity was normal in sera from psoriasis patients although some components such as urate were even elevated.

Serum concentrations of anti-acetylcholine-receptor (anti-AChR) antibody were measured in patients with myasthenia gravis. In those patients undergoing thymectomy concentrations were measured before and after the operation to see whether there might be a connection between the thymus and antibody production. We found no correlation between antibody concentration and either thymectomy or duration and severity of the disease before the operation. Our results suggest that if anti-AChR antibodies are the principal pathogenic factor in myasthenia gravis then immunological and neurophysical variables other than the total serum anti-AChR antibody concentration contribute to the severity of the disease.