Recent advances in human cellular immunobiology

Several recent advances in human cellular immunology will have increasing impact on surgical science. First, lymphocytes are composed of diverse subpopulations with different biological properties. Second, lymphocytes and phagocytes expressed distinctive cell surface markers that reflect the specialized function of each cell. Third, different subpopulations of lymphocytes probably have one or only a few specific functions rather than being multipotential. Despite the seemingly complex heterogeneity of the immune system, the component parts collaborate in a highly integrated fashion. The recent elucidation of suppressor cells and their interaction with effector cells, for example, is a major conceptual advance. Fourth, the technology of immunologic science has advanced significantly. More discriminating methods for detecting lymphocyte markers and the ability to physically separate and analyze lymphocyte subpopulations will permit increasingly more refined insights into normal and abnormal immune responses. A number of important advances at the molecular level involving the disciplines of immunogenetics and immunochemistry have also been described but are beyond the scope of this review. Much work remains, however, in correlating these in vitro observations in the laboratory with in viro activity in the patient. It is now evident that the outcome of an immune response (or lack of it) represents a net balance of different components in the immunologic network that determine the time course, intensity of response, and the actual mechanisms of antigen elimination. A better understanding of these component parts of a normal immune response, and their deviations in disease states, is essential for designing more sophisticated therapeutic manipulations of the immune system. Attempts at "immune manipulation" aimed at stimulating or depleting the entire system are no more likely to be successful or reproducible than are attempts to "manipulate" the entire endocrine system. More meaningful results will occur when one can deal with individual components of an immune response (such as suppression or killing) and can precisely monitor the consequences of altering them.