[The immunomodulating and immunoprotective activity of small ribonucleoprotein complexes (alpha RNPs) from the LRec-1sf cell line].

Effect of nuclear and released into culture medium alpha RNPs (N- and R-alpha-RNPs, resp.) produced by transformed rat embryo fibroblasts of serum-free cell line LRec-1sf on the nonsensibilized mouse splenocyte cytotoxicity (NK-mediated cell lysis) was studied. A preliminary treatment with N-alpha-RNPs resulted in decreasing K562 cell sensitivity to splenocyte cytotoxicity, whereas pretreatment of the splenocytes themselves exerted no cytotoxic effect. The target cell preincubation with R-alpha-RNPs had no influence on K562 cell resistance to NK cell cytotoxicity. The identical splenocyte preincubation was without action on their cytotoxic effect to LRec-1sf cells, however, resulted in an increase of the K562 cell lysis. The addition of R-alpha-RNPs into splenocyte/target cell mixtures had no influence on NK-mediated lysis, when K562 cells were used as a target cell line, but suppressed the NK-mediated lysis of LRec-1sf cells. The results of the present experiments suggest that alpha RNPs produced by LRec-1sf cell line exhibit the capacity for modulating both mouse NK cytotoxicity, and the transformed cell sensitivity to NK-mediated lysis.