Ultrastructure of normal human T cell subpopulations. Parallel tubular arrays in T gamma lymphocytes and clustered dense bodies in T mu lymphocytes.

Ultrastructures of normal T-cell subpopulations, T gamma and T mu cells, were studied. T gamma cells were isolated and identified by repeating the rosetting method; firstly, by E rosette formation with neuraminidase-treated sheep red blood cells (SRBC), and next by EA gamma-rosette formation with ox red blood cells coated with IgG antibody (EAox). Before EAox rosetting, SRBC on isolated T cells were lysed by autologous plasma instead of ammonium chloride solution. Normal T gamma cells were heterogeneous with regard to their granules; the majority of T gamma cells had parallel tubular arrays (PTA) and a few had electron-dense granules. When ammonium chloride solution was employed to lyse SRBC, PTA were never observed; PTA in normal T gamma cells and in chronic lymphocytic leukemia cells with T gamma character both seemed to change into electron-dense granules after ammonium chloride treatment. In contrast to T gamma cells, T mu cells were characterized by clustered dense bodies, i.e. focal aggregates of electron-dense granules.