PEANUT LECTIN-BINDING SITES AND MUCINS IN BENIGN AND MALIGNANT COLORECTAL TISSUES ASSOCIATED WITH SCHISTOMATOSIS

An immunohistochemical and histochemical comparative study was carried out in benign and malignant colorectal tissues with and without schis tosomiasis. This included a quantitative determination of peanut lecti n (PNA)-binding sites and proliferating eel nuclear antigen (PCNA) exp ression and histochemical detection of mucin changes. 133 cases were s tudied, including 70 cases of colorectal carcinoma associated with sch istosomiasis (CCS) and 63 cases of colorectal carcinoma without schist osomiasis (CC). Significant differences were found in the type of muci n-containing carcinomas (MC) between CCS and CC. 65% of nontumorous mu cosa adjacent to MC of the CCS group expressed PNA-binding sites, sign ificantly higher than those of the MC in the CC group (31%). The nontu morous mucosa in cases of MC of the CCS group also showed a high perce ntage of sialomucin-predominant secretion (69%, vs 38% in MC of the CC group). Consistently, the presence of PNA-binding sites in MC tumors of the CCS group was increased, compared with that in the same subtype in the CC group (respectively 65% and 31% of strong positivity for PN A). However, no differences in expression of PNA and mucin changes wer e demonstrated in the surrounding mucosa and tumorous tissues of non-m ucin-containing carcinomas (NMC) between CCS and CC. The expression of PCNA was not different between CCS and CC and their subtypes. Our fin dings suggest a close relationship between mucin-containing colorectal carcinomas and schistosomiasis japonica.