A comparison of rainbow trout cell lines for their expression of the major histocompatibility complex genes and the induction of beta-2-microglobulin by dsRNA

Western blotting with polyclonal antisera to polypeptides of the rainbow trout major histocompatibility (MH) genes and reverse transcriptase-polymerase chain reaction (RT-PCR) were used to compare expression of MH genes in rainbow trout cell lines. One line was the spleen monocyte/macrophage-like RTS11, which grew loosely on plastic surfaces. Adherent cell lines were fibroblast-like RTG-2 from gonads and four epithelial-like cell lines from gill, intestine, liver and hepatoma: RTgill-W1, RTgutGC, RTL-W1, and RTH-149 respectively. All cell lines expressed a 45 kDa MHC class I alpha chain. All cell lines expressed beta-2-microglobulin (β2m), which was at 11 kDa, but detection was abrogated following trypsinization prior to cell collection. All cell lines expressed transcripts for MH class II alpha and MH class II beta genes; however, MH class II polypeptides were expressed only in RTS11, the only cell line from a lineage of antigen-presenting cells. We report here that double stranded RNA up regulates β2m and that these cell lines and antisera can be employed for studying MH regulation.