Hyperthermic effects on viability and growth kinetics of human lymphoblastoid cells

During clinical hyperthermia, various blood elements may be exposed to elevated temperatures. The effect of heat on human lymphocyte viability and human lymphoblastoid cell viability and growth was therefore measured. In the viability studies, cells were heated for different times and temperatures and stained with fluorescein diacetate either immediately of at various times after treatment; dye uptake was then analysed using fluorescence microscopy. There was no significant decrease in lymphocyte viability when assayed at 0 and 24 h after heating at 42-43 degrees C for varying times. Similarly, when proliferating lymphoblastoid cells were heated at 42-43 degrees C, there was no decrease measured in viability immediately after heating. However, in contrast to the lymphocyte results, a progressive decrease of lymphoblastoid cell viability was observed with increasing time after treatment. A nadir in viability was observed 48-72 h after heating, followed by a subsequent apparent recovery. This recovery showed a correlation with cell growth, as well as lysis of non-viable cells. The cell population doubling time was also lengthened, with longer doubling times observed for more severe heat treatments.