Saturation index of blood cell membrane fatty acids before and after IFN treatment in hairy cell leukemia.

Cells from the peripheral blood of 32 patients with hairy cell leukemia (HCL) were analyzed for cell membrane fatty acid composition. A consistent and significant change was found in the relative amounts of stearic and oleic acid components, which is expressed as the saturation index (SI), the ratio of stearic to oleic acid content. In all patients, SI was reduced in the erythrocytes, leukocytes, and platelets. On extended treatment with interferon, the hematological improvement was accompanied by an increase in SI. In two patients, one deteriorating after cessation of treatment and the other on a low maintenance dose of interferon, concurrent influenza infection induced temporary improvements in the blood cell counts, as well as increase in SI values. These results indicate that endogenous interferon can also be effective in inducing hematological and SI improvement in this disease. The relevance of low SI values and concomitant increase in membrane fluidity to the malignant transformation is discussed. It is proposed that one effect of interferon is to reduce the production of growth factors by reducing the malignant cell mass.