The effects of RU 41.740, a glycoprotein immunomodulating agent derived from Klebsiella pneumoniae, on intra-abdominal abscess formation in mice.

The prophylactic and therapeutic efficacies of the immunomodulating agent RU 41.740 (a glycoprotein extract from Klebsiella pneumoniae) were studied in a murine model of intra-abdominal abscess formation with Bacteroides fragilis, Escherichia coli, and bran as an abscess-potentiating agent. Parenteral injection of RU 41.740, either before or after injection of an abscess-inducing mixture (AIM), was associated with significantly diminished incidence and size of abscesses. Abscess incidence and size were significantly decreased by oral administration of RU 41.740 after, but not before, AIM injection. Abscess formation and resolution are the results of complex interactions of host defence mechanisms with bacteria and potentiating agent, and RU 41.740 has been shown previously to activate both macrophage and neutrophil function. These results indicate that activation of non-specific defences may protect against abscess development in chronic sepsis.

Tumour enhancement associated with induction of abscesses in mice bearing a transplantable solid tumour.

A model of intraabdominal sepsis in the tumour-bearing host was established in order to study the interactions between host, tumour and infecting organisms. BALB/c mice bearing a transplanted tumour were given an intraperitoneal inoculum containing Bacteroides fragilis, Escherichia coli and bran as an abscess-potentiating agent. Tumour-bearing mice formed abscesses which were not significantly smaller than in controls except late in tumour growth. The bacterial contents of the abscesses were not significantly different to controls. In contrast, mice given an abscess-inducing mixture at or near the time of tumour cell inoculation had tumours which were significantly larger than in controls. The mechanism of tumour enhancement is not known.