MRI-negative, bone scintigram-positive in early osteonecrosis of the knees.

Nontraumatic avascular necrosis (AVN) of bone is a well-reported complication of glucocorticoid therapy for immunologic and malignant disease. We present the case of a 13-year-old girl with no history of trauma who presented with a 5-day history of increasing pain in both knees after cord blood transplantation for acute lymphoblastic leukemia. Plain film and magnetic resonance imaging (MRI) were reported as normal.

Intestinal IgA plasma cells of the B1 lineage are IL-5 dependent.

Two lineages of B cells, designated B1 and B2 cells, have been identified based upon their origins, anatomical distribution, cell surface markers, antibody repertoire and self-replenishing potential. B1 cells are maintained by self-renewal of cells resident in the peritoneal cavity (PerC) and they utilize a limited repertoire of germline V-region genes, mostly directed against ubiquitous bacterial antigens such as phosphoryl choline (PC). B2 cells are replenished from bone marrow precursors and use a larger repertoire of immunoglobulin V-region genes.