Mammalian (human, mouse, and rabbit) white blood cells (lymphocytes) maintained in culture respond to a brief incubation at an elevated temperature (at or above 41 degrees C) by (i) the new and (or) enhanced synthesis of a small number of proteins (the so-called heat-shock proteins; HSPs) having molecular masses of approximately 110 000, 100 000, 90 000, 70 000, 65 000, and 26 000 daltons and (ii) the depressed synthesis of proteins normally made at 37 degrees C. The HSPs synthesized in culture by human, rabbit, and mouse (peripheral and splenic) lymphocytes are similar in number, molecular mass, and distribution on two-dimensional (isoelectric focusing and sodium dodecyl sulfate--polyacrylamide) electrophoretic gels to those synthesized in vivo by lymphocytes in hyperthermic mice. Since the level of hyperthermia used to induce HSP synthesis in mouse lymphocytes in vitro and in vivo is of a magnitude (41 degrees C) also used to promote thermotolerance in mice and is similar to temperatures attained during febrile episodes in rabbits and in humans, we suggest that the in vitro and in vivo synthesis of HSPs by mouse lymphocytes, demonstrated in this study, represents a relevant, physiological response which mammalian lymphocytes may normally use to survive periods of thermal stress.
Animals Carbon Radioisotopes