This book has expanded classic concept of immunology. Immunoglobulins have been widely discovered to be produced by many non-B cells. The non B cell-derived Igs display multifunction, which not only includes antibody activities and cellular biological functions under physiological conditions, but also directly participate in the pathological process of malignant tumour and immune-related diseases. This book provides new perspectives and a solid foundation for medical students, basic and clinical scientists to re-understand and broaden the physiological and pathological significance of Ig.