Comparison of heat-shock-induced and lipopolysaccharide-induced protein changes and tumoricidal activity in a chicken...

The functions of a chicken mononuclear phagocytic cell line MQ-NCSU were examined after exposure to nonthermal (lipopolysaccharide, LPS) and thermal (heat shock, HS) treatments. The protein profiles and tumoricidal factor activity of MQ-NCSU cells exposed to 15 micrograms LPS under control (41 C) temperatures expressed enhanced synthesis of classical 23-, 70-, and 90-kDa HS proteins (HSP), a heat-inducible 32-kDa protein (P32), and a novel LPS-induced 120-kDa protein (P120). In comparison to LPS treatment, MQ-NCSU cells exposed to 45 C (HS) expressed HSP23, HSP70, HSP90, and P32 but not P120. Combined exposure of MQ-NCSU cells to HS (45 C) and LPS (15 micrograms) induced an alteration in the initial and optimal expression and duration of synthesis of the HSP and the LPS-induced P120. The tumoricidal activity of supernatants from LPS-treated and untreated MQ-NCSU cells cultured at 45 C was significantly depressed as compared with the controls (cultured at 41 C). The supernatants collected from LPS-treated and untreated MQ-NCSU cultures maintained at 41 C were exposed to 45 C temperature for up to 48 h. The tumoricidal potential of these supernatants was not affected. The present study demonstrates that LPS exposure induces several "stress" proteins in macrophages, some of which have molecular similarity with the classical HSP. In addition, LPS induces a unique 120-kDa protein not produced following HS alone, which may serve as a differential protein associated with activated or tumoricidal phenotype of macrophages. Heat shock suppresses the tumoricidal potential of LPS-treated MQ-NCSU cells in a regulatory manner that does not appear to be a result of thermal denaturation of the tumoricidal factor secreted in the culture supernatant.