Rituxan is seeing a lot of use these days. Although technically only having formal indications for rheumatoid arthritis and non-Hodgkin's lymphoma, it is being used for a number of off-label indications, and in general the results seem to be overall encouraging. In terms of renal disease, Rituxan is being used for the treatment of membranous nephropathy, lupus nephritis, ANCA-associated vasculitis, and antibody-mediated rejection of kidney transplants, among other things.
There are two major Rituxan dosing regimens in use. One common regimen is to give 375mg/m2 iv every week for 4 weeks.
It's often more convenient to give another regimen, which is 1000mg iv x 1 then another 1000mg 2 weeks later.
The duration of giving further "maintenance" Rituxan is not well worked out--overall the medication is still relatively new--but one common way to do it is to give 1000mg iv every 4 months.
Since the antibody is against the CD20 molecule on B-cells, you can perform a CD20 blood count to see whether the drug is having an effect--in general it is quite efficacious.