B lymphocyte-typing for prediction of clinical response to rituximab
1 Department of Internal Medicine, Division of Rheumatology and Immunology, Medical University Graz, Auenbruggerplatz 15, Graz, A-8036, Austria
2 Internal Medicine, Hospital Barmherzige Brueder, Bergstrasse 27, Graz-Eggenberg, A-8020, Austria
Arthritis Research & Therapy 2012, 14:R161 doi:10.1186/ar3901Published: 6 July 2012
The prediction of therapeutic response to rituximab in rheumatoid arthritis is desirable. We evaluated whether analysis of B lymphocyte subsets by flow cytometry would be useful to identify non-responders to rituximab ahead of time.
Fifty-two patients with active rheumatoid arthritis despite therapy with TNF-inhibitors were included in the national rituximab registry. DAS28 was determined before and 24 weeks after rituximab application. B cell subsets were analyzed by high-sensitive flow cytometry before and 2 weeks after rituximab administration. Complete depletion of B cells was defined as CD19-values below 0.0001 x109 cells/liter.
At 6 months 19 patients had a good (37%), 23 a moderate (44%) and 10 (19%) had no EULAR-response. The extent of B lymphocyte depletion in peripheral blood did not predict the success of rituximab therapy. Incomplete depletion was found at almost the same frequency in EULAR responders and non-responders. In comparison to healthy controls, non-responders had elevated baseline CD95+ pre-switch B cells, whereas responders had a lower frequency of plasmablasts.
The baseline enumeration of B lymphocyte subsets is still of limited clinical value for the prediction of response to anti-CD20 therapy. However, differences at the level of CD95+ pre switch B cells or plasmablasts were noticed with regard to treatment response. The criterion of complete depletion of peripheral B cells after rituximab administration did not predict the success of this therapy in rheumatoid arthritis.