Ischaemic injury to femoral head induces apoptotic and oncotic cell death.

AIMS: The mechanism of cell death in ischaemic osteonecrosis of the femoral head is not clear. Therefore, this study was designed to clarify the mode of cell death following ischaemic osteonecrosis of the femoral head in an established pig model. METHODS: Morphological assessment, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) assay, detection of DNA laddering and transmission electron microscopy studies were performed to determine whether apoptosis is one of the pathways of cell death following ischaemic osteonecrosis of the femoral head. RESULTS: Mode of cell death was investigated from 2 to 14 days following the surgical induction of ischaemia. Ischaemic femoral heads showed morphological evidence of cell death by oncotic and apoptotic pathways in earlier stages of osteonecrosis. TUNEL positive cells were seen from 2 to 14 days following the induction of ischaemia. DNA samples obtained from ischaemic femoral heads following the induction of ischaemia showed nucleosomal ladders indicating apoptotic cell death. Electron micrographs also showed morphological changes associated with apoptosis. CONCLUSIONS: This study demonstrates that oncosis is not the sole mechanism of cell death following ischaemic injury of the femoral head. Both apoptosis and oncosis are involved as a result of ischaemic injury to the femoral head.

B cell loss leading to remission in severe systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) pathogenesis is mediated in part by autoantibodies. We describe a patient with central nervous system lupus who developed a loss of B cells with associated hypogammaglobulinemia and sinopulmonary infections requiring intravenous immunoglobulin. The SLE went into complete remission. Of 18 reported patients with SLE developing persistent hypogammaglobulinemia, only 5 patients including ours had a nearly complete loss of circulating B cells. Of those whose SLE and B cell status was reported, 5/5 with B cell loss and 1/10 without B cell loss experienced a durable response of SLE (p = 0.002). These cases illustrate that B cell ablative therapies may have efficacy for SLE.