Evaluation of surface markers on normal human lymphocytes containing parallel tubular arrays: a quantitative ultrastructural study.

Normal lymphocytes from the peripheral circulation represent a heterogenous population of cells with different surface markers and different functions. Some of these lymphocytes contain cytoplasmic inclusions called parallel tubular arrays (PTA). which can only be identified with certainty under the electron microscope. It is not known whether this ultrastructurally defined lymphocyte constitutes the major cell type of the T-Iymphocyte population. B-lymphocyte population. or third population of lymphocytes (i.e.. K cells. I cells, M cells. null cells). or is unrelated to any of these immunologically defined lymphocyte subpopulations. The purpose of this study was to determine if this morphologically identifiable lymphocyte constitutes the major cell type of any of these three lymphocyte subpopulations. A quantitative ultrastructural analysis of PTA-lymphocytes was performed on a lymphocyteenriched fraction using three surface marker assays commonly used to identify the three major populations. Spontaneous rosettes formed with sheep erythrocytes (E-rosettes) were used as a marker for T lymphocytes. Sheep erythrocytes sensitized with rabbit 1gM antibody and coated with mouse complement (EAC-rosettes) were used as a marker for B lymphocytes. Human group 0, type R,R2 erythrocytes sensitized with Ripley anti-CD serum to identify the Fc receptors (EA6,-rosettes) were used as a