Differentiation of lymphoid cells of the B cell series according to membrane and cytoplasmic determinants.

Previous investigations have shown that a large proportion of normal human lymphocytes bearing membrane-bound IgM have also independently moving IgD molecules on their surface. Since it is known that in the majority of chronic lymphatic leukaemias (CLL) high numbers of lymphocytes with easily detectable membrane IgM can be found, we investigated CLL cells for the presence of membrane-bound IgD. In all 18 cases studied, high proportions of cells bearing surface IgD and IgM could be found. In none of the 18 cases crystalline Ig inclusions could be detected.