Immune capacity of the chicken bursectomized at 60 hours of incubation: transplantation of bone marrow cells of the bursectomized chickens into cyclophosphamide‐treated newly hatched recipients

Abstract

Chickens bursectomized at 60 h of incubation are known to be able to produce immunoglobulins (Ig) but not specific antibodies. In the present work bone marrow (BM) cells of 2- and 10-week-old embryonically bursectomized (Bx) chickens were transferred to newly hatched cyclophosphamide-treated chickens for the purpose of studying whether the transplanted cells home into the bursa and gain a capacity to produce specific antibodies. BM cells of normal 2- and 10-week-old chickens were transferred as controls. Cells of 2-week-old control (Co) and of 2- and 10-week-old Bx chickens could to some extent reconstitute serum Ig of the recipients, but were totally incapable of homing into the bursa and of restoring the specific antibody production. Only BM cells of 10-week-old Co chickens could restore the production of specific antibodies without homing into the bursa, indicating their postbursal nature. These findings indicate (a) that 2- and 10-week Bx BM cells have irreversibly bypassed the bursal phase of education, (b) that also the normal BM at the age of 2 weeks contains cells that are capable of Ig but not of specific antibody synthesis and (c) that bursal microenvironment is not necessary for isotype switch, but is essential for creation and expansion of the antibody repertoire.

B cell precursors in chick embryos surgically bursectomized at 72 h of incubation

“…One could predict that in the absence of bursal anlage, precursor B cells might accumulate in the bone marrow of embryo bursectomized (E-Bx) chicks. However, no evidence was obtained that bone marrow cells from 2-and 10-wk-old E-Bx birds were capable of homing into the neonatal bursa of cyclophosphamidetreated birds and restoring the humoral immune system [15]. In the present study we demonstrate by parabiosis and cell transfer experiments the presence of precursor B cells in embryos surgically bursectomized at 72 h of incubation, using sex chromosomes and the genetically polymorphic B cell antigen Bu-1 [16] as markers.…”

“…This selective disappearance of prebursal B cell precursors or change in the hemopoietic stem cell population during the late embryonic and early postembryonic period occurred in both normal and Te-treated chick embryos [13]. Recently the presence of precursor B cells was studied in chickens surgically bursectomized at 60 h of incubation [15]. One could predict that in the absence of bursal anlage, precursor B cells might accumulate in the bone marrow of embryo bursectomized (E-Bx) chicks.…”