[Effect of C-reactive protein on natural killer activity]

The relationship between natural killer (NK) activity of peripheral blood lymphocytes and serum C-reactive protein (CRP) concentration was analysed in patients with carcinoma of the lung and metastatic pulmonary tumors. Significant reverse correlation (r=-0.43) was found between NK activity against OAT cells or K-562 cells and serum CRP concentration. For the elucidation of the mechanism of suppressive activity of CRP against NK activity, in vitro effects of CRP on NK activity was studied. Relative NK activity compared to control decreased to 23.3 +/- 5.6% in experiment adding 1.0 mg/dl of CRP into NK assay mixture (p less than 0.001). Relative NK activity was also strongly inhibited in experiment preincubating lymphocytes with CRP. The decrease of NK activity with CRP was depending on the concentration of CRP.