Influence of adjuvant radiation therapy in breast cancer on PWM induced Ig-secretion by blood lymphocytes in vitro.

The capacity of PWM (poke-weed mitogen) to stimulate Ig-secretion by blood lymphocytes was examined before and at various times after local radiation therapy (46.0 Gy) for breast cancer. It was observed that the secretion of IgM, IgA and IgG were significantly reduced at completion of radiation therapy. Secretion of IgM was reduced to the highest relative extent (approximately 10% of the pretreatment value). Thereafter there was a recovery of the Ig-secreting capacity which, however, remained below the pretreatment level, 12-18 months after completion of radiation therapy. The capacity of PWM-stimulated blood lymphocytes to secrete specific antibodies against morbilli and herpes simplex virus was also significantly impaired after radiation therapy. The reduction of Ig-synthesis in vitro was not correlated with the increase in the ratio between numbers of monocytes and lymphocytes in peripheral blood after radiation therapy. Possible explanations for these results are discussed.