@Jonathan Edwards
I went back and re-listened to the video and am writing here what Dr. Mikovits said about determining eligibility for rituximab:
She says that only ME/CFS patients whose CD20 and CD23 cells have "expanded" should get (low dose) rituximab. And she seems to be indicating that this was about 30% of the ME/CFS patients she worked with. (She said the rituximab dosage should be much lower than for treating cancer.)
I'm not clear if by "expanded" she's referring to a direct measurement of the number of CD20 and CD23 cells in blood, or if "expanded" refers to a culture (incubation) of "peripheral blood" that she mentioned.
Regarding the latter, she said they found that in 30% of patients that the CD20/23 cells would grow in culture unchecked (expanded?) and become "immortalized" and eventually a tumor (a "chronic lymphocytic leukemia") if the natural killer cells didn't "see" those cells and kill them. And that ME/CFS patients have an NK cell problem in this regard.
I haven't had a chance to read it yet, but there's a free pdf download of the pertinent chapter of the 2014 book
Chronic Fatigue Syndrome, which is referenced while Dr. Mikovits is talking, on the following webpage:
Innate Immune Changes in the Peripheral Blood of Chronic Fatigue Syndrome Patients: Risk Factors for Disease Progression and Management (pp. 91-130)
Edit: Page 101 of the book/download explains some about CD20 and CD23, and rituximab.