Influence of medium composition on the observed variability of erythrocyte susceptibility. B. divergens clone 2802C D5 was inoculated into media prepared with RBC of varying degrees of susceptibility and sera from different origins (5 different FCS – and 2 different sheep sera – SS) used at 10% (A) or at different concentrations (10, 20, 30 and 40%) (B and C). Each A₄₀₅ data point represents the average value of the triplicate wells, and the error bars indicate the standard deviation. This experiment was also conducted with the clone Rouen F5 with similar results.