Abstract
A cell wall protein that is ordinarily complexed to the lipopolysaccharide endotoxin in gram-negative bacteria [Salmonella typhosa, Escherichia coli] was separated by the use of aqueous phenol. The protein is active as a B[bone marrow-derived]-cell mitogen and polyclonal activator of murine lymphocytes, including the C3H/HeJ strain which is a nonresponder to lipopolysaccharide or lipid A.