Modulation of inflammatory reactions by previous contact with Escherichia coli in rats.

OBJECTIVE

To find out if contact with Escherichia coli had any effect on a subsequent inflammatory reaction induced by the same micro-organism.

DESIGN

Controlled laboratory study.

SETTING

University laboratory.

MATERIAL

Male white Wistar rats divided into groups of 6 to 10.

INTERVENTIONS

Pretreatment with sponges soaked in 1 x 10(9) heat killed E. coli inserted either subcutaneously into the back or intraperitoneally into the right hypochondrium, and 14 days later repeat challenge. Controls received sponges soaked either in saline with penicillin and streptomycin or with carrageenan lambda. Pretreatment with live or heat killed E. coli or E. coli endotoxin injected intradermally or intraperitoneally (controls were given saline).

MAIN OUTCOME MEASURES

Number of white cells present in the inflammatory infiltrate and the peritoneal cavity, and titres of anti-E. coli antibody.

RESULTS

Pretreatment of Wistar rats with heat-killed or live E. coli (ATCC 25922) was followed by increase in the cellular infiltrates at the site of subsequent challenge with the same micro-organism. The effect was not related to the synthesis of anti-E. coli antibodies.

CONCLUSION

Surgical patients have commonly been in previous contact with E. coli; this might affect their inflammatory reactions if they came into contact with the organism after operation. Further studies are needed to clarify the precise mechanisms and clinical relevance of these findings.