Lectin staining of peritoneal mesothelial cells in vitro

A survey of lectin-binding specificities present on rodent and human mesothelial cells propagated and maintained in tissue culture was made using fluorescein isothiocynate conjugated (FITC) lectins. Rodent and human cells exhibited cell-associated fluorescence following exposure to the FITC-lectins from C. ensiformis, T. vulgaris, A. hypogaea, E. cristagalli and B. simplicifolia, but not with lectins from G. max and D. biflorus. Rodent cells were also positive for FITC-M. pomifera lectin binding. Human, but not rodent, cells were positive for FITC-T. purpureas lectin binding. Exposure of rabbit mesothelial cells in vitro to FITC-lectins that bound to the cell surface resulted in the appearance of discrete loci of putatively intracellular fluorescence. Exposure of cells to ferritin-labelled T. vulgaris lectin at 37 degrees C for as little as 7.5 minutes resulted in the appearance of ferritin-size particles in intracellular vesicles. These results demonstrate 1. the presence of lectin-binding sites in and on peritoneal mesothelial cells from rodents and humans and 2. a possible role of such sites in mediating the entry of lectin-like endogenous molecules into the vacuolar apparatus of these cells.