Identification of a lectin that induces cell death in developing chicken B cells

The bursa of Fabricius is required for the development of a diverse B cell repertoire in chickens. Bursal B cells are dependent on survival signals within the bursa and their removal from the bursa results in death by apoptosis. To find molecules that regulate B cell survival, a panel of mAb and lectins was screened for the ability to either accelerate or prevent B cell death in culture. The fucose-specific lectin Aleuria aurantia agglutinin (AAA) rapidly rendered B cells permeable to propidium iodide. Incubation with the lectin also accelerated the appearance of internucleosomal DNA fragmentation and nuclear condensation, characteristics of apoptotic cell death. On Western blots the lectin detects a single protein band of approximately 48-50 kDa molecular weight. AAA detects fucose in an alpha 1-6 linkage and the restriction of this fucose linkage to a single protein suggests that it may be functionally important in the regulation of cell survival.