Adherence properties of hairy cells.

The Hairy Cells (HC) from four patients with Hairy Cell Leukemia (HCL) were studied. These cells exhibited membrane properties of B-lymphocytes; quantitation of surface membrane immunoglobulins by the peroxidase labeled antibody technique showed an average number of 20,000 to 40,000 immunoglobulin molecules per marked cell. Observations by scanning electron microscopy (SEM) showed that HC have a great capacity to adhere quickly to glass coverslips, to phagocytose latex particles, and to resist trypsin treatment. These cells possess numerous inter cellular connections forming a network on the glass-coverslip, and thin cytoplasmic projections enabling them to adhere. When cells adhering to a support are stimulated by latex particles, they are able to phagocytose these particles and this results in the swelling of the cell due to the unpleating of numerous folds of the membrane. After this stimulation, HC appeared smooth. Our SEM analysis provides an explanation of the disappearance of the hairy appearance classically described. After trypsin treatment, the adhering HC remain on the glass even if they have suffered membrane damage. In conclusion, SEM examination of adhering cells and phagocytosis demonstrate the variability of the membrane aspect of the HCL cells under various culture conditions.