An increase in apoptosis of leucocytes and impaired clearance of apoptotic cells have been observed in patients with systemic lupus erythematosus (SLE). Apoptotic cells are likely to be a key source of autoantigens in SLE since they express many of the nuclear autoantigens relevant to this disease in surface blebs and apoptotic bodies. The clearance of apoptotic cells is usually a very rapid process such that few cells are usually seen in the extracellular environment in vivo. We report a case in which multiple apoptotic bodies were observed in the bone marrow of a patient with SLE complicated by an immune-mediated pancytopenia. We have subsequently examined the frequency of apoptotic cells, identified morphologically and by caspase-3 staining in bone marrow trephine samples taken from patients with SLE in our department over a 10 year period of follow-up. A high proportion of marrows contained apoptotic debris. An excess of necrotic cells was not observed. The novel demonstration of apoptotic bodies in vivo in patients with SLE is unusual and supports the notion that the marrow may be a target organ in the disease. Their abundance is also consistent with the hypothesis that normal clearance mechanisms are defective and/or overwhelmed in SLE.
- bone marrow
- systemic lupus erythematosus