Curdlan, a (1----3)-beta-D-glucan from Alcaligenes faecalis var. myxogenes IFO13140, activates the alternative complement pathway by heat treatment.

From the results of consumption experiments of guinea pig complement, Curdlan, a (1----3)-beta-D-glucan obtained from Alcaligenes faecalis var. myxogenes IFO13140, has been found to lack the ability to activate complement when unheated or preheated at either 40 degrees C or 50 degrees C. However, Curdlan heated at or above 60 degrees C increased complement consumption. This activation, dependent on the temperature of the Curdlan, was via the alternative complement pathway as assessed by cleavage of factor B into Ba and Bb fragments. These results suggest a substantial change must occur in Curdlan with heat treatment for alternative pathway activation.