Let me clarify, are you asking if rituximab (Rituxan) can help build up your platelets or are you asking if this medication can cause a decrease in your platelets count?
One side-effect associated with Rituxan is thrombocytopenia which is low platelet count. You can read more about thrombocytopenia at the following link: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001612/.
I really hope I have answered your question to your satisfaction; if I have, I would appreciate your "accepting" my answer; bonuses are always appreciated. If you have anything else you would like to ask prior to accepting, I would be happy to answer.
My oncologist has suggested that a four-week (once per week) infusion of Rituxin might cause an increase in my Platelet count.