OBJECTIVE: To assess the presence and phenotype of B-lineage cells in the bone marrow (BM) of rheumatoid arthritis (RA) patients after rituximab therapy. METHODS: Six patients were studied. BM aspirates were collected 3 months after the treatment and analysed using the four-colour flow cytometry. RESULTS: CD19+ (B-lineage) cells in BM samples varied from 0.1 to 3.25% in the lymphoid gate. CD34+ cells varied from 1.23 to 4.86%. The proportion of CD34+ cells committed to the B-lineage varied between 0 and 42.19%. Pro-B-cells were undetectable in one case. The majority of B-cell precursors were pro-B-cells in Patients 5 and 6 (50 and 62% of CD19+ cells, respectively), pre-B-cells in Patients 3 and 4 (64 and 70%) and immature B-cells in Patient 1 (44%). Detectable CD20 expression on CD19+ cells was either low or absent. Plasma cells varied from 0.01 to 0.36% of the total nucleated cells. There was a trend towards longer duration of clinical response in patients with evidence of more complete depletion in BM. CONCLUSION: In this small cohort of RA patients treated with rituximab, differences in proportion and phenotype of CD19+ BM cells were detected. These differences suggest variation in the degree of depletion achieved and correlate with time to relapse. Although pro-B-cells are not targeted directly by rituximab as they do not express CD20, the levels were unexpectedly low.
OBJECTIVE: To assess the presence and phenotype of B-lineage cells in the bone marrow (BM) of rheumatoid arthritis (RA) patients after rituximab therapy. METHODS: Six patients were studied. BM aspirates were collected 3 months after the treatment and analysed using the four-colour flow cytometry. RESULTS:CD19+ (B-lineage) cells in BM samples varied from 0.1 to 3.25% in the lymphoid gate. CD34+ cells varied from 1.23 to 4.86%. The proportion of CD34+ cells committed to the B-lineage varied between 0 and 42.19%. Pro-B-cells were undetectable in one case. The majority of B-cell precursors were pro-B-cells in Patients 5 and 6 (50 and 62% of CD19+ cells, respectively), pre-B-cells in Patients 3 and 4 (64 and 70%) and immature B-cells in Patient 1 (44%). Detectable CD20 expression on CD19+ cells was either low or absent. Plasma cells varied from 0.01 to 0.36% of the total nucleated cells. There was a trend towards longer duration of clinical response in patients with evidence of more complete depletion in BM. CONCLUSION: In this small cohort of RApatients treated with rituximab, differences in proportion and phenotype of CD19+ BM cells were detected. These differences suggest variation in the degree of depletion achieved and correlate with time to relapse. Although pro-B-cells are not targeted directly by rituximab as they do not express CD20, the levels were unexpectedly low.
Authors: Magda Nakou; Georgios Katsikas; Prodromos Sidiropoulos; George Bertsias; Eva Papadimitraki; Amalia Raptopoulou; Helen Koutala; Helen A Papadaki; Herakles Kritikos; Dimitrios T Boumpas Journal: Arthritis Res Ther Date: 2009-08-28 Impact factor: 5.156
Authors: Maria Rehnberg; Sylvie Amu; Andrej Tarkowski; Maria I Bokarewa; Mikael Brisslert Journal: Arthritis Res Ther Date: 2009-08-17 Impact factor: 5.156