Characterization by immunoperoxidase of the lymphocytes with bundle- shaped tubular (BST) inclusions in human normal peripheral blood

In six normal subjects, no surface immunoglobulins were detected on blood lymphocytes containing bundle-shaped tubular (BST) inclusions, after incubation with anti-human IgM peroxidase-labeled Fab'2 fragments. These Fab'2 fragments from pepsin-digested sheep anti-human immunoglobulins revealed human mu kappa, and lambda chains. These results suggest that the BST inclusions do not belong to B lymphocytes but belong to T cells and/or a third lymphocyte population, including K cells and precursors of T and B cells.