Histocompatibility Requirements for Cellular Cooperation in the Chicken

Abstract

In the studies regarding the B cell differentiation we have been using the chemical bursectomy model in the chicken. Newly-hatched chickens are treated with cyclophosphamide on four consecutive days starting on the day of hatching. The treatment results in virtually complete and life-long humoral immune deficiency, including atrophy of the bursa of Fabricius and absence of germinal center formation. On the fourth day of life such birds are transplanted with different lymphoid cells to be studied, and the effects of the transplantation are assessed at the age of 4–6 weeks using morphological and functional criteria. On the basis of these studies we have found that during late embryonic development and around the time of hatching the bursa contains a special cell population which we have chosen to call bursal stem cells (1–4). These cells are still unable to produce antibodies by themselves. When transplanted into cyclophosphamide-treated recipients they induce a full functional and morphological restoration, including normalization of the bursal morphology and germinal center formation in the spleen. In order to differentiate further these cells need a close contact to the bursal reticulum.

Supported of experiments where bursal stem cells were transplanted into NIH Contact N01-CB-43971.