ONTOGENY OF IMMUNE RESPONSE TO SKIN ALLOGRAFTS IN RELATION TO LYMPHOID ORGAN DEVELOPMENT IN AMPHIBIAN XENOPUS LAEVIS DAUDIN

The response of larval and adult Xenopus to first set skin allografts was studied by examination at regular intervals of the external appearance of the grafts and of serial sections through the graft region. Operations were performed on all stages of larvae ranging from those with rudimentary to those with mature lymphoid organs. Larvae received single allografts from either larval or adult donors, skin from the latter being a good morphological marker: adults received adult skin only. Control autografts were also applied to both larval and adult toads. All autografts were accepted; no incompatible phenomena were observed. Both adults and larvae, even those operated at the most immature stage of development, were able to repond immunologically to the skin allografts. The response was similar in larval and adult toads and included a lymphocytic invasion of the graft which disappeared when destruction of the graft was near completion. This invasion was correlated with the state of development of the lymphoid organs of the host: if these organs were immature at the time of application of the graft, the invasion was delayed but eventually occurred when the host reached a more advanced larval stage. The capacity to invade a graft with lymphocytes could be correlated with the lymphoid maturation of the thymus. These results support the view that the allotransplantation of tissues in immature amphibian larvae, before acquisition of immunological competence, does not necessarily preculude the possibility of an immune response to the same tissues in more mature larvae. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company