oup antigen common to erythrocytes and lymphocytes.
Freshly drawn lymphocytes showed the simultaneous presence of p., y, K, and A determinants on the cells of 16 patients (13 with CLL and 3 with W.M.).
Further experiments performed in six of these patients proved that this
mixed staining pattern can be considered as a false polyclonal appearance
since only p. and K chains were detected on the cell surface after removal
of S.Ig either by trypsin or after antibody induced redistribution followed
by incubation for 6 hr. These results, showing that the actual cell product
was monoclonal, should be considered when interpreting some previously
published data.’8 Moreover, in four of the six patients thus studied, we have
demonstrated that the mixed staining pattern was due to an anti-IgG antibody
activity of the 5.1gM receptors.”’ The incidence of this anti-IgG activity of
membrane bound 1gM appears to be relatively high among CLL patients.
It is analogous to the strikingly high percentage of serum monoclonal 1gM