Natural killer activity in peripheral lymphocyte population following local radiation therapy.

The natural killer (NK) activity of peripheral lymphocytes against 51Cr-labelled Chang or K562 cells was tested using a 4 h release assay before and after postoperative radiation therapy for mammary carcinoma. NK activity against K562 was significantly reduced at completion of therapy (a total target dose of 45.0 Gy) and restituted 3 to 4 months later. NK activity against Change cells exhibited a slight but non-significant decline at completion of therapy followed by an overshoot 3 to 4 months later. The frequency of Fc-IgG receptor bearing lymphocytes was decreased at completion of therapy and largely restored after 3 to 4 months.