I had 4 infusions of rituxin, can Facelift be done a week after last treatment?

Rituxin is a potent medication with significant side effects and other drug interactions. A facelift probably could be done safely week after the last infusion depending on a number of variables. I would prefer that you wait at least 2 to 3 weeks before proceeding with an elective facelift but this is a very subjective opinion.

 The medicine that you're currently taking us to help ramp down your immune system.   I don't know what type of blood borne disease (ie Lymphoma) that you may have but it's obvious that this medication is helping control that.  Overall it does not sound like you're a good candidate for elective surgery. Proceeding with surgery in your particular circumstance may lead to severe complications including severe infection. 

Facelift surgery is a major elective cosmetic surgery that has some inherent risks and complication such as flap necrosis and pour healing.  Undergoing chemotherapy compromises the immune system and therefore increases the risks of sever complications. You need to discuss this matter with your oncologist and your primary care physician. A board certified surgeon would not risk his patient's healing process. You may need to get a second cosultation as when would be an appropriate time to get a facelift after your chemotherapy.