Membrane characteristics and functional analysis of human T and B lymphocytes : a contributions to the analysis of immunodeficiency in children

Concepts of the immune system in man change along with models based on experimental research (52). In the past three decennia the function of human lymphocytes~ their differentiation pathways and their disorders have been unraveled by a close collaboration between animal and human immunologists. The analysis of "experiments of nature", immunodeficiency diseases in man, has not only proven (or rejected) models developed for the human immune system, but also generated new directions for investigation (13). At the same time our understanding is still fragmentary and hence treatment of immunodeficiency diseases in Children still in its infancy. Current therapeutic trials are based upon the classical model of the human immune system (15). In this model lymphocytes are divided into two compartments: T lymphocytes and B lymphocytes. Both originate from bone marrow stem cell(s) (76) and differentiate along separate pathways. Immunodeficiency diseases are analyzed within this framework and are viewed as differentiation blocks within two separate cell-lineages