The ultrastructural morphology of T lymphocytes in B-chronic lymphocytic leukaemia: a study with monoclonal antibodies and the immunogold technique.

T-lymphocytes from five patients with B-cell chronic lymphocytic leukaemia (B-CLL) were analysed by light (LM) and electron microscopy (EM) by means of the immunogold technique with monoclonal antibodies combined with E rosettes. LM analysis confirmed the existence of a population of E+ lymphocytes unreactive with the OKT3 monoclonal antibody. The EM study showed that E+ lymphocytes from B-CLL can be distinguished morphologically from the leukaemic B-cells which were identified by their labelling with FMC4 (anti HLA-Dr). Within the E+ fraction two cell types were seen which differed both in reactivity with OKT3 and ultrastructural morphology. T3+ lymphocytes are similar to normal T3+, T4+ cells: they have high nucleocytoplasmic (N/C) ratio and few cytoplasmic organelles. Their reactivity with OKT3 is, however, considerably weaker than that of normal T3+ lymphocytes. T3- (E+) lymphocytes, on the other hand, are characterized by low N/C ratio, active Golgi, lysosomal granules and parallel tubular arrays. These cells resemble normal T gamma lymphocytes which comprise cells with the membrane phenotypes: T3+, T8+, M1- and T3-, T8-, M1+. These results provide further evidence for a T-cell imbalance in B-CLL and help define better the cellular basis for this abnormality.