Variants of hamster fibroblasts resistant to Ricinus communis toxin (ricin)

Area of Science:

• Cell Biology
• Toxicology
• Biochemistry

Background:

• Ricin, a toxic lectin from Ricinus communis, poses a significant biological hazard.
• Understanding cellular resistance mechanisms to ricin is crucial for developing countermeasures and for basic research.

Purpose of the Study:

• To isolate and characterize baby-hamster kidney (BHK) cell lines resistant to ricin.
• To investigate the phenotypic changes associated with ricin resistance, particularly regarding cell surface lectin binding.

Main Methods:

• Normal BHK cells were treated with the mutagen methyl-N-nitro-N-nitrosoguanidine.
• Cells were selected for resistance by exposure to high concentrations of ricin.
• Ricin-resistant cell lines were analyzed for their ability to bind labeled ricin and other lectins (RCA, Axinella polyploides, Lens culinaris lectin, concanavalin A, Phaseolus vulgaris lectin).

Main Results:

• Stable ricin-resistant BHK cell lines were successfully isolated.
• Some resistant cell lines exhibited normal ricin binding, while others showed reduced binding, indicating varied resistance mechanisms.
• Loss of receptors for other similar lectins (RCA, Axinella polyploides) was observed in some lines.
• Altered binding patterns were noted for lectins with different sugar specificities (Lens culinaris lectin, concanavalin A).
• Cross-resistance and increased sensitivity to other plant lectins were observed in some ricin-resistant lines.

Conclusions:

• Mutagenesis and selection can generate stable ricin-resistant BHK cell lines with distinct phenotypes.
• Ricin resistance is associated with changes in cell surface lectin receptor expression and binding.
• These variant cell lines provide valuable models for studying ricin toxicity and cellular defense mechanisms against lectins.