Analysis of the Lytic Step in the Herpes Simplex Virus Antibody-Dependent Cellular Cytotoxicity System

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Abstract
An antibody-dependent cellular cytotoxicity (ADCC) system in which herpes simplex virus[HSV]-infected [human] Chang liver cells are used was assessed for its dependency on cellular energy, RNA and protein synthesis and cytoskeletal structures such as microfilaments and microtubules. The cytotoxic reaction was only slightly inhibited when glycolysis was blocked in a glucose-free medium containing 10-2 M 2-deoxy-D-glucose. It was more substantially inhibited when respiration was blocked with 10-2 M sodium azide. The reaction was totally ablated only when glycolysis and respiration were suppressed. This inhibitory effect of energy deprivation was mediated solely at the level of the effector cell. RNA synthesis or protein synthesis by the effector cells was not required, as shown by the fact that neither actinomycin D, cycloheximide nor emetine significantly inhibited ADCC. The ADCC reaction was partially inhibited by cytochalasin B, whose inhibitory effect was rapidly reversible and was completely and irreversibly inhibited by cytochalasin A. Cytochalasin A acted on the effector cells rather than the target cells. The reaction was partially inhibited by colchicine, whose inhibitory effect was directed solely against the effector cells and was slowly reversible. The inhibitory effects of cytochalasin B and colchicine, when used in tandem at submaximal inhibitory concentrations, were slightly more than additive. A cooperative role may exist for effector cell microfilaments and microtubules in mediating ADCC. Kinetic studies of ongoing HSV ADCC reactions after initial centrifugation showed that the lytic step requires expenditure of metabolic energy and intact function of microfilaments and microtubules. The ADCC process against HSV infected Chang liver cells can possibly be resolved into adhesion and lytic steps. The lytic step can be readily distinguished from the adhesion step by its increased sensitivity to low ambient temperature or metabolic energy deprivation, its sensitivity to thermal inactivation, its requirements for extracellular divalent cations and its dependence on normal function of microfilaments and microtubules.