Low natural killer‐cell activity and immunoglobulin levels associated with smoking in human subjects

Abstract Previous studies have shown that smoking is associated with a high incidence of certain malignancies and a high incidence of metastatic spread of melanoma. The purpose of the present study was to examine whether this high incidence of malignancy could be associated with certain aspects of immune function believed to be important in restricting tumour growth. Age‐and sex‐matched smoking and non‐smoking normal subjects and male, smoking and non‐smoking melanoma patients, were studied for the natural killing (NK) activity of their blood leukocytes against cultured melanoma and Chang cells. The levels of the various immunoglobulin classes in their sera and the E rosette levels of the normal subjects were also assessed. The results indicate that the NK activity of blood leukocytes from both normal subjects and melanoma patients who smoked was significantly lower against cultured melanoma cells than that of non‐smokers. Smokers were also shown to have lower IgG and IgA Immunoglobulin levels in their sera compared to non‐smokers but no differences in the percentage of E‐rosetting (T) cells was detected. Recent studies provide some basis for the belief that the low NK activity and immunoglobulin levels in smokers may be related. These results further suggest that a closer examination of the effects of this environmental hazard on the immune system and its relation to malignancy is needed.