ADMINISTRATION OF ANTI-ASIALO GM(1) SERUM INCREASES ABERRANT CRYPT FOCI INDUCED BY 1,2-DIMETHYLHYDRAZINE IN THE LARGE-BOWEL OF RATS

We investigated the influence of the administration of anti-asialo GM( 1) antibody on aberrant crypt foci (ACF) formation induced by a single injection of 1,2-dimethylhydrazine (DMH). At four weeks after the inj ection of DMH (20 mg/kg body weight), the number of ACF and aberrant c rypts were counted. Most ACF appeared in the distal large bowel, accou nting for approximately 60% of the total ACF in both groups. Rats admi nistered anti-asialo GM(1) had significantly more ACF in the distal co lon, the rectum and the total large bowel as compared to control rats. A similar tendency was observed for the number of aberrant crypts. Th e increased number of ACF resulting from the administration of anti-as ialo GM(1) was not accompanied by the enlargement of ACF size in every part of the colon. This study demonstrated that the administration of anti-asialo GM(1) at the initiation stage leads to an increase in ACF as well as aberrant crypts in the distal colon, rectum and total larg e bowel probably via the suppression of natural killer cells.