Chemiluminescence and immune cell activation. I. Early activation of rat thymocytes can be monitored by chemiluminescence measurements.
Immediately after the addition of concanavalin A, rat thymocytes respond, in the presence of luminol, with a burst of chemiluminescence (CL) that can be conveniently monitored in an ordinary liquid scintillation spectrometer. Peak CL is reached after 50 sec. Addition of catalase suppresses 65% of the CL, suggesting that H2O2 generation may be its major source. CL with different kinetic characteristics can also be generated by the calcium ionophore A23187. Our rat thymocytes contain approximately 0.1% endogenous macrophages. Bone marrow-derived rat macrophages also respond to concanavalin A or A23187 stimulation with a burst of CL. However, the kinetic properties of CL as well as the inhibition of CL by catalase in these cells differ markedly from those of thymocyte preparations, suggesting that the major portion of the CL in rat thymocytes actually originates in T lymphocytes. Because CL measurements allow the monitoring of very early events in cell activation and because of the simplicity of the technique, CL measurements may become a useful method for the study of lymphocyte activation, of macrophage-lymphocyte interactions, as well as for the rapid screening for specificity and reactivity of T lymphocyte populations.