In most of the cases of CLL most of the circulating blood lymphocytes bore
Ig molecules on their surface since immunofluorescence study of living cells
in suspension showed positive reactions at the lymphocyte surface with antisera
to Ig chains. After labeling in the cold, the positive cells were characterized
by the presence of numerous small spots regularly distributed all
around the cell surface. These positive lymphocytes were easily distinguishable
from occasional labeled polymorphonuclears and monocytes by phase contrast
examination of each microscopic field and also from killed cells which exhibited
homogeneous intracytoplasmic staining. The fluorescence pattern of the positive
lymphocytes was usually faint and uniform in a given patient, the
number, size and brightness of the spots being very similar on all positive
lymphocytes. In contrast, the fluorescence pattern varied from patient to
patient. When the cells exhibiting a diffuse membrane fluorescence were