Anti-Clostridium difficile bovine immunoglobulin concentrate inhibits cytotoxicity and enterotoxicity of C-difficile toxins

Clostridium difficile diarrhea and colitis result from the actions of bacterial exotoxins on the colonic mucosa. This study examined the ability of hyperimmune bovine colostral antibodies to neutralize the biological effects of these toxins. Anti-C. difficile bovine immunoglobulin concentrate was prepared from the colostral milk of Holstein cows previously immunized with C. difficile toxoids. The anti-C. difficile bovine immunoglobulin concentrate contained high levels of bovine immunoglobulin G specific for C. difficile toxins A and B, as evaluated by enzyme-linked immunosorbent assay, Anti-C. difficile bovine immunoglobulin concentrate neutralized the cytotoxic effects of purified toxin A and toxin B on cultured human fibroblasts, whereas control bovine immunoglobulin concentrate had little toxin-neutralizing activity. Anti-C. difficile bovine immunoglobulin concentrate also blocked the binding of toxin A to its enterocyte receptor and inhibited the enterotoxic effects of C. difficile toxins on the rat ileum, as measured by an increased rat ileal loop weight/length ratio (63% inhibition; P < 0.01), increased mannitol permeability (92% inhibition; P < 0.01), and histologic grading of enteritis (P < 0.01 versus nonimmune bovine immunoglobulin concentrate). Thus, anti-C. difficile bovine immunoglobulin concentrate neutralizes the cytotoxic effects of C. difficile toxins in vitro and inhibits their enterotoxic effects in vivo. This agent may be clinically useful in the prevention and treatment of C. difficile diarrhea and colitis.