Lymphocytes isolated from the peripheral blood of patients with nonmalignant and malignant disorders were studied for fluidity of
membrane lipids and lateral mobility of
concanavalin A (Con A) receptors. The degree of fluidity of the surface
membrane lipid core was monitored quantitatively by fluorescence polarization analysis using the probe
1,6-diphenyl-1,3,5-hexatriene embedded in
lipid regions of the surface membrane of intact cells. Mobility of Con A surface receptors was determined by the cap-forming ability after binding of fluorescent Con A. The present studies were performed on lymphocytes from 28 patients with
malignant lymphomas, 22 patients with
leukemia, 28 individuals who either were healthy or had nonmalignant disorders, and 5 patients with
carcinoma. The results showed that lymphocytes and mononuclear cells from patients with
malignant lymphomas and
leukemias have a more fluid
lipid layer in their surface membrane than do lymphocytes obtained from healthy individuals or from patients with other malignant and nonmalignant disorders. This increase in membrane fluidity was less pronounced in lymphocytes isolated from leukemic patients in clinical remission and from leukemic patients receiving treatment with
steroids. The results also show a marked difference in the cap-forming ability of lymphocytes from patients with
malignant lymphomas or
leukemia as compared with lymphocytes from patients with non-malignant disorders or
carcinoma. Lymphocytes isolated from
lymphoma and
chronic lymphatic leukemia patients during remission stages of the disease exhibited a higher cap-forming ability. The cap-forming ability of cells from patients with
chronic lymphocytic leukemia was unaffected by treatment with
steroids. The present results, which are in line with previous observations, have shown that normal lymphocytes can be characterized by a low degree of
lipid fluidity but a high degree of mobility of Con A receptors, whereas leukemic lymphocytes are characterized by a high degree of
lipid fluidity but a low degree of mobility of Con A receptors. These results confirmed our general hypothesis on the dynamic interrelation between
membrane lipids and
membrane protein receptors, and they indicate that the widely accepted term "membrane fluidity" requires better consideration for different membrane components.