General immune status in cancer therapy

Theoretical considerations in immunotherapy, such as the timing of challenge, which could rank second to reduction of tumour volume in producing lasting regressions, are outlined and illustrate the need for tests to monitor immune status. Estimation of immunosuppression, in order to define cancer therapy schedules providing least interference with what might be useful host response to tumour, is described in terms of a reliable radioimmunoassay method assessing lymphocyte replicating ability (LRA). The extent of the effect of radiation or radiomimetic drugs in vitro can be shown upon LRA in response to phytohaemagglutinin or to irradiated cells. In clinical research LRA assessment makes a satisfactory test of the general immune state of patients undergoing cancer treatments, given that matched control subjects are available throughout the period of observation to allow repeated assessment of the relative response. An assured relative response seems feasible if all examinations are related to a common standard, the stored reference lymphocyte. Conversely a relative response can be measured against stored target cells.