Depression of lymphocyte replicating ability in radiotherapy patients

Abstract

The effects of radiation upon circulating lymphocytes have been measured by two independent means, one monitoring the level of cytogenetic damage appearing in these cells, the other monitoring changes in their proliferative response to stimulation in culture by phytohaemagglutin (PHA). Response to PHA can be expressed quantitatively as lymphocyte replicating ability (LRA), i.e. the degree of 3 H-thymidine uptake measured under standardized conditions. Varying degrees of depression of LRA have been noted within a group of patients undergoing a wide range of radiotherapeutic procedures. The concomitant cytogenetic studies indicate that although cells bearing radiation damage do persist in the circulation after irradiation their numbers are insufficient to account for the marked reduction seen at the same time in LRA. It appears that the reduction is largely due to a fall in the number of thymusdependent lymphocytes in the circulatory pool.

Lymphocyte Replication in Lung Cancer Patients Undergoing Radiotherapy

“…Lymphocyte counts also decreased significantly following radiotherapy in lung cancer patients and are in general agreement with the findings of other investi gators in lung cancer [2,3,5,9,10] and other malig nancies (11,13].…”

“…There have been conflicting reports regarding cellmediated immunity in lung cancer patients. Some in vestigators have reported varying degrees of depression of lymphocyte transformation in lung cancer patients following radiotherapy [1][2][3][4][5] while others have not observed such a reduced response [6][7][8], To date there is very little quantitative data on lymphocyte survival in lung cancer patients undergoing radiotherapy. This report describes in vivo and in vitro survival of lympho cytes in lung cancer patients before, during and follow ing radiotherapy.…”

Radiation and immunotherapy: a synergistic combination

“…In contrast, others described RT as an immunosuppressant (29). Lymphocytes are exquisitely sensitive to the effects of RT (30)(31)(32), and irradiating the tumor target could potentially eliminate antitumor immune activity. This, along with the general ineffectiveness of RT on local control and of early immunotherapies on systemic disease, dampened enthusiasm for pursuing the combination.…”

Histological Analysis of Lymphocyte Subsets Infiltrated into Mouse Tumor Tissue Exposed to Local Irradiation

“…Radiotherapy has been widely believed to suppress the host's immune system [1][2][3][4][5][6][7], Recent studies, how ever, have demonstrated that an enhanced local im mune reaction, i.e., infiltration of numerous T lym phocytes in and around the tumor tissue, can be seen transiently during radiotherapy [8 11]. To learn whether this phenomenon really represents an ac tivated immune reaction specific against tumor cells, it is necessary to investigate the composition and func tion of the infiltrated lymphocytes.…”