Lymphocyte Purification, Growth, Cloning and Functional Assays

Lymphocytes comprise an extremely heterogeneous mixture of cells, differing in both specificity and function. Thus the immune system can recognise and respond to an enormous range of antigens and can mount functionally distinct types of responses to different forms of antigen (Chap. 1). The classical reductionalist approach to the problem of lymphocyte heterogeneity has been to obtain homogeneous populations of cells. In this way the signals acting on different populations of cells and the consequences of such signals can be determined. Homogeneous populations of cells have been prepared by either the extensive purification of mixed populations of cells or, more rigorously, by the growth and cloning of single cells from a mixed population.