The effects of rosette nanotubes with different functionalizations on channel catfish (Ictalurus punctatus) lymphocyte viability and receptor function

The effects of self-assembled rosette nanotubes (RNTs) with different surface functionalizations (K-, TBL-, RGDSK1/TBL9-) on fish lymphocyte viability and effector function were examined using channel catfish (Ictalurus punctatus) as a model. Surface functionalization was an important determinant of nanotoxicity. Lysine-functionalized RNTs (K-RNTs) consistently caused the greatest decline in lymphocyte viability while aminobutyl-functionalized RNTs (TBL-RNTs) had the least effect on lymphocyte viability. This trend was conserved across the multiple cell lines examined (both B- and T-cells). However, the absolute change in viability was distinct for each type of lymphocyte studied. Following RNT exposure, the two channel catfish B-cell lines tested, 3B11 and 1G8, had similar toxicity profiles for each of the RNT functionalizations examined. This was in contrast to the T-cell line tested, 28S.3, which had more viable cells remaining in culture post RNT exposure and suggests differences in toxicity based on the lymphocyte examined (B- versus T-cells). Lastly, exposure of cells to K-, TBL- or Arg-Gly-Asp-Ser-Lys peptide-functionalized RNTs (RGDSK-RNTs), significantly reduced the ability of cells to phagocytose through the channel catfish immune receptor, leukocyte immune-type receptor (IpLITR). Sub-lethal levels of RNT exposure affected the ability of immune cells to elicit this effector response in vitro and was concentration- and functionalization-dependent. Together, these data demonstrate that distinct classes of fish lymphocytes respond differentially to RNT exposure and that RNT functionalization impacts both lymphocyte viability and effector functions.