EPITHELIOID AND FIBROBLASTIC CELL-LINES DERIVED FROM THE ILEUM OF AN ADULT HISTOCOMPATIBLE MINIATURE BOAR (D D HAPLOTYPE) AND IMMORTALIZED BY SV40 PLASMID/

Intestinal explants were maintained for weeks in a growth medium conta ining collagenase for progressive digestion to derive finite cell line s from the ileum (64 lines) or from the colon (8 lines) of a boar. Two ileal cell lines retaining either a fibroblastic or an epithelioid mo rphology have been used to derive heteroploid cell lines (IPI-1 and IP I-2) immortalized by transfection with an SV40 plasmid (pSV3-neo). The IPI-1 cells were found of fibroblastic lineage. The IPI-2 cell line g ave rise to morphologically heterogeneous colonies ranging from typica l epithelial cells to colonies of more-elongated cells. A crisis occur red during subcultivation of IPI-2 leading to the isolation of the IPI -2I cell line with a 24 h doubling time and a 21% plating efficiency. Epithelial nature of IPI-2I cells was supported by ultrastructural ana lysis of the cell monolayers. Differentiated cells were found to expre ss microvilli at the apical cellular membrane and desmosomes connectin g adjacent cells. Stable epithelioid phenotypes were obtained only fro m the IPI-2I cell line by multiple subcloning. These cells were found to express characteristics of both epithelial and mesenchymal cells by positive immunostaining with monoclonal antibodies reacting either wi th keratin 18 filament of simple epithelia or with vimentin filament t ypical in vivo of mesoderm. The lack of villin expression and the abse nce of transepithelial resistance have to be related to a poor differe ntiated state of this cell line. All these immortalized cell lines wer e permissive to the replication of microorganisms pathogenic for pig ( Salmonella chloleraesuis, Salmonella typhimurium and tissue culture-ad apted strains of transmissible gastroenteritis virus). The collection of finite and continuous cell lines will help to develop in vitro meth ods for long-term propagation of freshly isolated epithelium or three- dimensional organ culture in pig. In addition, the IPI-2I cell line pr ovides a new model to study the conversion from a transformed to a non transformed phenotype as incorporation of 2% dimethyl sulfoxide in the growth medium to repress large tumor antigen expression led to the pr ogressive disappearance of cytokeratin 18 positive cells with, over a week, the death of the surviving vimentin-positive cells.