Cytolysis of Nucleated Cells by Complement: Cell Death Displays Multi-Hit Characteristics

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 80; no. 12; pp. 3816 - 3820
• Main Authors: Koski, Carol L., Ramm, Louise E., Hammer, Carl H., Mayer, Manfred M., Shin, Moon L.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.06.1983; National Acad Sciences
• Subjects: Antibodies; Cell death; Cell Line; Cell lines; Cell Nucleus - physiology; channels; complement component C5b; Complement System Proteins - immunology; Cytolysis; Cytotoxicity, Immunologic; Dose response relationship; Dyes; Erythrocyte membrane; Erythrocytes; Erythrocytes - physiology; Hammers; Hemolysis; Humans; Kinetics; Leukemia, Myeloid - immunology; lymphocytes T; Lymphoma; man; T lymphocytes; T-Lymphocytes - immunology
• DOI: 10.1073/pnas.80.12.3816
• ISSN: 0027-8424

Lysis of nucleated cells by complement was studied to determine whether the lytic process by C5b-9 conforms to a one-hit mechanism as in the case of erythrocytes. Two nucleated cell lines, Molt 4 and U937, derived from human T lymphocytes and histiocytes, respectively, were employed as targets. The antibody-sensitized cells were used to develop the titration curves, measuring cell death as a function of limiting quantities of human C6 or C5,6 complex in the presence of an excess of other complement components. The cytolysis curves generated in both experiments were sigmoidal, in sharp contrast to the monotonic curves observed in lysis of erythrocytes treated similarly. The sigmoidal curves of cytolysis indicate a cooperative action of several molecules of C6 or acid-activated C5,6 complex, C(56)a. In contrast to the multi-hit characteristics of cytolysis, does--response measurements of the release of86Rb indicated that only one effective molecule of C6 per cell is required for assembly of a86Rb-releasing channel. This divergence indicates that lysis requires formation of several channels or, alternatively, assembly of large channels that are formed by several molecules of C6. Because prior studies with erythrocyte ghosts have shown that only a single effective molecule of C6 is required for assembly of a transmembrane channel, regardless of size, we prefer to interpret the multihit characteristics of nucleated cell lysis as an indication of a multi-channel requirement, rather than channel enlargement.