Constitutive synthesis of heat shock protein (72 kD) in human peripheral blood mononuclear cells: implications for use as a clinical test of recent thermal stress.

There is no clinical laboratory marker to enhance the diagnosis of recent thermal stress in humans. The 72 kD heat shock protein, HSP 72, which is rapidly synthesized after heat stress could be useful in the diagnosis of illnesses associated with heat stress. In humans HSP, 72 is rapidly synthesized after thermal stress; however, conflicting data suggest it may also undergo low level constitutive synthesis. If HSP 72 is constitutively synthesized, a semi-quantitative test will be necessary to detect recent heat stress; if not, a qualitative test would be sufficient, peripheral blood mononuclear cells were chosen for this investigation because they can be isolated from a small sample (clinically acceptable) of blood. Following heat stress Western analysis and autoradiography of one- and two-dimensional electrophoresis samples demonstrated low levels of HSP 72 in unstressed cells. HSP 72 increased with heat stress, and remained elevated for up to 48 h. HSP 72 mRNA was detectable in small amounts in nonheat stressed cells. Heat stress increased HSP 72 mRNA 1 and 2 h after stress and remained elevated for 6 h. HSP 72 persists long enough to be potentially useful as a diagnostic probe of recent heat injury; however, a semi-quantitative assay will be necessary.