My understanding (which of course could also be wrong
) is that Rituximab attacks all the B-cells that are in the body at the time of the infusion (and the days thereafter), including memory B-cells, and is also effective at killing most of them, but
new B-cells that are produced after the Rituximab effect wears off are the same B-cells as before, i.e. they have the same immunity as before, so you don't need new vaccinations because the new B-cells that are produced after Rituximab are just as effective as the old B-cells were that Rituximab destroyed. (huh, that was complicated, hope I don't confuse everyone).
I was discussing this last night w/a friend of mine from another medical group (she has POTS and some overlap with me but also has several medical conditions that I do not have). She will possibly be having Rituximab for the rest of her life (vs. I am doing a series of six infusions over the course of one year). She had similar concerns as you re: immuno-suppression and spoke with her infusion nurse and she paraphrased her explanation (below):
"B-Cells are our 'memory' immune cells. When our bodies get a cold and fights it, the B-Cells keep a small copy of the virus and the DNA used to fight that virus. That way if that same virus is introduced into your system your body can fight it. Rituxan implants a chemical code into the cells that tells them that they need to commit suicide. It seems like a bad idea to kill the cells that remember how to fight basic things. In talking to my nurse she said that the bone marrow is what reproduces cells, so the memory is probably in the bone marrow more then the actual cells. So we're probably okay".
She used the word "probably" twice but it kinda reassured me that (hopefully?!) the memory is in the bone marrow and these are the B cells that survive?
Re: what you said about new B cells having the immunity, my understanding is that the B cells remain at zero for the entire year of treatment and that this is the goal (to keep them at zero) so it would have to be some other mechanism that continues to fight viruses, etc.
In Jan, I will not have had a cold, flu or traditional illness in five years. I did the first two Ritux infusions in July/Aug (now mid Oct) but I still have not gotten sick. I have been exposed to both my step-daughter and niece while they were sick (and my niece even had strep throat right before I was with her) but I did not catch it. I've been in restaurants, at hospitals, my infusion center, and regular public places but thus far, have not caught anything. But I continue to do IVIG so this might be protective. I am also extremely on the auto-immune side.
But that being said, for the time during which Rituximab is active, you don't have the B-cells in your blood (or many fewer of them than you usually would have) and that's also why you are more susceptible to usual infections (common cold, flu etc.) during that time.
It seems to be the case but my doctor said that he has not had any patients get sick after getting Ritux (including those who flew on an airplane immediately after the infusion)- which does not pertain to me and I have not been well enough to fly since mid 2013.
So that's my argument: there is an immunosuppressive effect of Rituximab and if it's not EBV and not autoantibodies, but instead it is another virus that causes the CFS, then Rituximab will make you less effective at fighting that virus for some time.
This doesn't match with what my doctor has said so far (or with people in another medical group that I belong to who have done Ritux long term) but maybe ME/CFS is different? I had very high IgM+ and early antigen (EA+) titers to EBV for about 3 yrs post-mono until they finally went negative. But after Ritux, my EBV did not re-activate (that I am aware of, but we have not re-tested it). One of my daughter's best friends has mono right now (I was never exposed to her directly) so I am concerned about this but nothing that I can do.
This might explain why some CFS patients got much worse after Rituximab. Maybe their CFS is caused by Coxsackie or some other virus and now they are killing their B-cells with Rituximab and get immunosuppressed and then they are even less able to keep Coxsackie at bay and everything gets worse.
I honestly have no idea! I tested positive twice for Coxsackie B4 and Echovirus 11 from ARUP lab, and I suspect most people test positive for both herpes and enterovirus titers, especially IgG+, but I have no statistics on that!