OVINE SQUAMOUS-CELL CARCINOMA - IMMUNOCHARACTERISATION OF NEOPLASTIC-CELLS AND PERITUMOURAL CELLULAR INFILTRATE

An immunohistochemical characterisation of neoplastic cells and peritu moural cellular infiltrate of ovine squamous cell carcinomas (OSCC) in different stages of growth was carried out using a commercially-avail able panel of seven antibodies, and formalin-fixed and paraffin-embedd ed tissue samples. Neoplastic cells reacted with the anti-keratin mono clonal antibody RCK-102 and with an anti-keratin polyclonal antibody, whereas they were unreactive with the anti-keratin monoclonal antibody NCL-5D3. The tumour cells were unreactive with the anti-vimentin poly clonal antibody. Increased numbers of CD3+ T-lymphocytes, IgG-containi ng plasma cells and lysozyme+ macrophages were associated with precanc erous lesions (actinic keratosis) and with early OSCC. These results s how that early lesions of OSCC induce an in situ cellular and humoral immune response. In advanced OSCC, the number of CD3+ T-lymphocytes an d macrophages in the peri-and intratumoural cellular infiltrate remain ed high, whereas a significant decrease of IgG-containing plasma cells was found compared with early OSCC. This finding suggests an in situ decrease in the humoral immune response in advanced OSCC.