Virus Infections and the Immune Responses They Elicit

Various classes and subclasses of immunoglobulins have been recognized and their structures and properties elucidated. Interactions of T and B lymphocytes and macrophages in the induction of immune responses have been documented. Reactions of receptor immunoglobulins on B lymphocytes and the mechanism of synthesis of immunoglobulins in their progeny have been analyzed. Products of T lymphocytes activated by antigens and mitogens have been defined, and their effects on macrophages and other cells studied. Components of the complement system have been isolated and characterized, and the alternate path of activation of the complement system has been recognized. Less is known about the biologic importance of the cytotoxic system in which antibody sensitizes virus-infected target cells for destruction by non-specific effector (K) lymphoid cells. This has been shown to occur in vitro with herpesvirus-infected cells and could play a role in immunity and immunopathology. Model systems of viral infections should be useful in defining the importance of this phenomenon.