The Onset and Maturation of the Graft versus Host Reaction in Chickens

Abstract

The increase in wet weight of the host spleen following implantation of competent chick, juvenile or adult chicken spleen has been shown to be paralleled by increases in dry weight and in content of RNA, DNA, and protein. No increase in the spleen-weights of the hosts was found when non-competent spleen cells from chick embryos or 1-day-old chicks were used as donor. The onset of immunological competence with respect to this transplantation reaction has been shown to occur at about 5 days post-hatching when the spleens were implanted into embryos at 8 days of incubation and the host spleens removed 10 days later. The ability of chicken spleen cells to evoke hepatomegaly and splenomegaly of the embryo hosts increased with age and was greatest after 21 weeks of age. Sometimes a reduction in whole body-weight of the embryo hosts also occurred. Although no sex differences in host spleen-weight were observed when 8– 15-day-old male chick spleens were used as grafts, a significant increase in female host liver- and spleen-weights (compared with those of the male hosts) was noted when 8–21-day-old female chick spleens were used as grafts. Spleen cells from male chickens of 6–17-weeks old did not produce much greater splenomegaly than those from young chicks and there were no sex differences between the host embryo spleen-weights. However, when female spleen tissue from 6-to 20-week-old chicks was used as graft a significant increase in the hepatomegaly and splenomegaly of the female hosts above those in the male hosts was observed. No sex differences were obtained in embryo host spleen-weights when small implants of adult male or female spleen cells were used as grafts. Thymus, liver, and bone-marrow from competent donors have been found to be nearly as effective as spleen in producing splenomegaly of the embryo hosts.