ABSTRACT
This chapter discusses models of antibody-dependent cellular cytotoxicity (ADCC) and their relationship to natural killer (NK) activity. Such a discussion immediately becomes complex because ADCC may be mediated by many different types of cells; furthermore, these antibody-directed killer cells can lyse a varied spectrum of targets. Despite the inability to physically or morphologically separate cells with NK activity from cells with ADCC activity, some available evidence suggests that these activities may represent distinct cell types. For example, H. S. Koren and M. S. Williams have presented evidence based on competitive inhibition assays which suggests that cells exhibiting NK and ADCC activity represent distinct subsets. Phylogenetically, it is likely that NK-like forms of cytolysis pre-aged the development of ADCC. Invertebrates exhibit a large array of cytotoxic cells capable of target cell cytolysis in the absence of antibody or T-cell recognition.
