Abstract
Structural changes were regularly observed in Brown-Pearce rabbit carcinoma cells that had been brought into contact, in the presence of complement, with rabbit serum containing an antibody that reacts specifically with a distinctive sedimentable constituent of the carcinoma cells. The cellular changes appeared rapidly and were accompanied by an equally rapid loss of viability. The structural changes, as disclosed by histological and cytological methods, including phase contrast microscopy, were described in detail and illustrated. Essentially they were characterized by the entrance of considerable quantities of fluid into the cell, together with swelling and disorganization of its cytoplasm, vesiculation and rupture of the bulk of its cytoplasmic particles, and rapid and virtually complete loss of cytoplasmic basophilism. The plasma membranes, though stretched thin about the swollen cytoplasm of the altered cells, and otherwise changed also, remained unruptured during many hours' observation. The nuclei of the altered cells, however, remained relatively un-changed, their membranes persisting unruptured and their sap remaining wholly transparent and undiminished in amount for long periods, while within it the chromatin retained its staining properties, though sometimes becoming clumped and marginated; by contrast, the nucleoli of the treated cells promptly shrank and lost much of their affinity for the basic dyes. The experimental conditions under which the structural changes became manifest were given in detail, together with an analysis of the findings and brief mention of certain of their implications for cytology and immunology.