Cholesterol content and fluidity of normal human and chronic lymphocytic leukaemia lymphocytes in relation to serum cholesterol level

No significant difference was found between a group of healthy individuals and a group of patients with unequivocal chronic lymphocytic leukaemia (CLL) in either the cholesterol content or the fluidity of the circulating lymphocytes, there existing similar degrees of variation within each group. Serum cholesterol level (free and total) varied considerably among the donors, but there was no significant difference between the two groups. Moreover, lymphocyte cholesterol content did not correlate with serum cholesterol level. Furthermore, blood lymphocyte count varied independently of serum cholesterol level.

Cholesterol was quantitatively determined by a specific microanalytical procedure involving gas-liquid chromatography. The fluidity of living lymphocytes was measured as the degree of fluorescence depolarisation of the probe molecule diphenylhexatriene. The lymphocyte preparations were free from other cell types and could be considered representative of the populations in the whole bloods. Cryopreserved samples showed slight losses in cholesterol.

These findings on all three counts contradict the evidence on which Inbar and Shinitzky [21] advanced their hypothesis, invoking cholesterol as a bioregulator of CLL through its influence on the surface membrane fluidity of lymphocytes. They do not, however, exclude the possible influence of cholesterol on the clinical and haematological behaviour of individual patients.