Lesions in Escherichia coli cell walls caused by the action of mouse complement.

Characteristic lesions formed by mouse complement were visible in electron micrographs of cell walls treated with aminoethylisothiouronium bromide and then incubated with normal mouse serum . However, lesions could not be detected in cell walls recovered from the blood of normal mice after intravenous injection. Lesions were not produced by either heated or complement deficient mouse sera in any of the experiments. After incubation with normal or complement deficient mouse serum cell walls were surrounded by a layer probably made up of complement components and immunoglobulins. This layer was less evident when the sera had been heated at 56° for 1 hour. Numerous lesions formed by the action of guinea-pig complement were found in cell walls recovered from the animal after intravenous injection.