Cytolytic T-Cell Granules: Biochemimcal Properties and Functional Specificity

Abstract

Murine, cloned cytolytic NK- and TK-cells may be classified as large, granular lymphocytes possessing a prominent Golgi complex and active ergastoplasma (Fig. 1). The granules are characterized by a dense homogeneous core surrounded by an area of vesicular structures and delimited by a bilayer membrane. Ultrastructural studies showed the positioning of granules towards the conjugation site of killer-target conjugates and the apparent release (secretion) of granule contents into the interstitial space (1–5). Subsequently, two types of membrane lesions poly PI (160 Å diameter) and poly P2 (~70 Å diameter) became detectable on target membranes and on vescicular bodies (4,5,6) (Fig. 2). These studies led to the hypothesis that the granules contain the factors responsible for membrane lesion assembly and that they represent the cytolytic principle of cloned cytolytic NK and TK cells (7). Similar conclusions were reached by Henkart et al in the antibody dependent cytotoxicity system and with a rat lymphoma line that expressed NK-like cytotoxicity.