The project will focus on the structure and function of leukocyte membrane receptors and surface antigens. The project has three interrelated long-term objectives. The first of these is to characterize normal leukocyte membrane surface markers for their distribution on different leukocyte types and for their order of appearance during leukocyte maturation. The project will not be restricted to any one leukocyte type, but will encompass the spectrum of bone marrow nucleated cells, including erythroid precursors and megakaryocytes. The findings with normal leukocytes form the basis for the second objective of the project, to find and characterize leukemia-specfic membrane markers and determine which of these may have prognostic significance for early determination of important clinical subtypes or stages of leukemic disease. The third goal is to analyze lymphocyte membranes by scanning electron microscopy and determine the distribution and association of different types of receptors on individual cells.