probably the best immunology text for med school
Abbas's Cellular and Molecular Immunology is structured in much the same way as his other textbook, Robbin's Pathology. Concepts are delineated in a clear and concise manner, although the illustrations are not quite as good as some other texts. Still, current alternatives (like Parham's The Immune System, itself a summary of Janeway's Immunobiology) are not quite as direct, as they offer details that are probably more interesting to immunologists than medical students.
(This is not to say that The Immune System is not helpful, but it's far less direct than this book.)