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Rheumatology (Oxford). 2007 Jan;46(1):29-36. Epub 2006 May 30.

Bone marrow B-lineage cells in patients with rheumatoid arthritis following rituximab therapy.

Author information

  • 1Centre for Rheumatology, University College London, London W1T 4JF, UK. maria.leandro@ucl.ac.uk

Abstract

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.

PMID:
16735454
[PubMed - indexed for MEDLINE]
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