A number of CD20 mAbs are now used in clinical practice or are in different stages of development (Table 3). Most of them such as rituximab, 90Y-Ibritumomab, tositumomab, ofatumumab and Obinutuzumab (GA 101) have been FDA approved for use in NHLs and RA. All anti-CD20 mAbs are biochemically and functionally divided into two distinct subtypes such as rituximab-like type I and tositumomab-like type II as shown in Table 2 [75,76].