Objective: Juvenile idiopathic arthritis (JIA) is the most common
rheumatic disease in children. The exact causes of disease are still
poorly understood. It seems that B cells have several functions in JIA,
including production of autoantibodies, antigen presentation,
production of cytokines, and activation of T cells. Here, we aimed to
evaluate B-cell lineage and its precursors in the bone marrow of
patients with JIA. Methods: Twenty consecutive patients with JIA were
enrolled in this study. JIA is subdivided into three groups of
Pauciarticular, Polyarticular, and Systemic JIA. Bone marrow
mononuclear cells were separated. Then we analyzed the immunophenotype
of the JIA patients by flow cytometry. After separation, the
mononuclear cells were stained specific for B cell lineage [CD10, CD19
and CD20], T cell lineage [CD3] and non specific lineage [CD34, HLA-DR
and TdT]. Findings: Flow cytometric study of bone marrow showed that
JIA patients had low level of CD10, CD19, and CD20. Polyarticular
patients had lower level of D10, CD19, and CD20 than pauciarticular JIA
patients and systemic onset JIA patients had lower levels than both of
them. Conclusion: Decreasing of B cell precursor in bone marrow is one
of mechanisms for pathogenesis of JIA and the more decreased B cell
precursors in bone marrow are, the worst severity of the disease is.
Significant differences in CD10 content of bone marrow were detected
between the polyarticular and pauciarticular groups. So, it seems that
polyarticular JIA patients had lower percentage of pre B cell stage