This book is the edited proceedings of the seventh conference or international workshop on white cell differentiation antigens held in Harrogate UK in June 2000. Although originally confined to white cells like Topsy these meetings have grown to encompass many other related cell types, such as dendritic cells endothelial cells, platelets, and red blood cells. Originally, these meetings involved a wide range of interests from the basic science of the molecules through to their practical applications. Over the years, …