The aim of this project was to develop a Luminex Xmap method for quantifying factor H. Factor H is a 150 kDa protein that acts as a regulating protein in the alternative pathway of the complement system. In a coupling reaction the magnetic beads were coupled to the catching antibody, and the concentration of 3 µg/10⁶ beads was chosen. The detecting antibody was tested at concentrations 0,5 µg/mL, 1 µg/mL, 2 µg/mL,

4 µg/mL and 6 ug/mL and from these 4 ug/mL was chosen. The test material was made up by 39 serum samples from blood donors at the blood donor centre at Akademiska sjukhuset in Uppsala. Two samples were analysed to estimate the intra serial variation. Sample A coefficient of variation within the analysis of 4,5 % and sample B 7 %. A regression analysis was made and gave an Rof 0,99 for sample A and 0,99 for sample B. The serum concentration of factor H was compared with earlier results using ELISA. However the correlation between the two methods were rather low (r=0,19, R²=0,03). The conclusion is that further work is needed to investigate why there is no correlation and find ways to improve it.