Susceptibility of renal tubular cells to lymphokine-activated killer (LAK) cells: application of culture system using a collagen gel matrix

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Abstract
Monolayer cultures of renal tubular (hKEC) cells were established. These cells formed empty spheroids after 2–3 weeks of culture in a collagen gel matrix. A subcellular polarity from the apex to basement was induced in these “spheroidal” hKEC cells. The weak expression of laminin at the outer surface was evident on spheroidal but not on monolayered hKEC cells. The regulation of HLA-ABC, DR, and intercellular adhesion molecule-1 (ICAM-1) antigens on hKEC cells in the gel matrix was investigated utilizing digestion of gel matrix by collagenase. Enzymatic digestion of the collagen gel did not significantly affect the surface expression of HLA-ABC and ICAM-1, but reduced HLA-DR expression as shown by flow cytometry. The MHC and ICAM-1 molecules on both spheroid-forming and monolayered hKEC cells were upregulated by adding a supernatant of mixed lymphocyte reaction (MLR) and recombinant human interferon (IFN)-γ. HLA-DR antigen expression was inconsistently induced on the hKEC cells cultured in collagen gel without MLR supernatant or IFN-γ. In contrast, no HLA-DR expression was found on monolayered hKEC cells in the absence of MLR supernatant or IFN-γ. Spheroid-forming hKEC cells, when dispersed by enzymatic digestion, were more susceptible to cytolysis by lymphokine-activated killer (LAK) cells than were the enzymatically dispersed, monolayered cells in the51Cr-release assay. The LAK cells were seen to migrate into the collagen gel and kill the hKEC cells. Thus, LAK cells may function to favor the acceleration of graft rejection. The culture of renal tubular cells in collagen gel provides a useful in vitro system for analyzing the allogeneic response.