In vitro response of lymphocytes of normal and ovine squamous cell carcinoma-bearing sheep to phytomitogens and tumour extracts

Ovine squamous cell carcinoma: immunocharacterisation of neoplastic cells and peritumoural cellular infiltrate

An immunohistochemical characterisation of neoplastic cells and peritumoural cellular infiltrate of ovine squamous cell carcinomas (OSCC) in different stages of growth was carried out using a commercially-available panel of seven antibodies, and formalin-fixed and paraffin-embedded tissue samples. Neoplastic cells reacted with the anti-keratin monoclonal 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 polyclonal antibody. Increased numbers of CD3+ T-lymphocytes, IgG-containing plasma cells and lysozyme+ macrophages were associated with precancerous lesions (actinic keratosis) and with early OSCC. These results show that early lesions of OSCC induce an in situ cellular and humoral immune response. In advanced OSCC, the number of CD3+ T-lymphocytes and macrophages in the peri- and intratumoural cellular infiltrate remained 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.

Ploidy and proliferative characteristics of sheep epidermal squamous cell carcinoma determined by flow cytometric DNA analysis

Multiple biopsies from each of 22 primary sheep epidermal squamous cell carcinomas were analysed by flow cytometry to determine the G0/G1 modal DNA content ("ploidy") and cell cycle characteristics within each tumour. Ten of 12 tumours where aneuploidy was present demonstrated uniform intra-tumour aneuploid populations regardless of the site of biopsy. Increasing tumour volume (from stage I/II to stage III/IV lesions) was associated with increased histological variability and ultimate heterogeneity of G0/G1 DNA content, whilst the mean numbers of S phase cells decreased. These features were consistent with the effects of variable tissue hypoxia seen with changes in effective vascularity in developing tumours. Decreasing histological differentiation was associated with an increase in numbers of cells synthesising DNA within 44 biopsies with measurable S phase, and, in stage I/II biopsies, correlated with an increased incidence of aneuploidy.