Accumulation of eosinophils and monocytes in lymphoid organs of chick-embryos. I. Effect of antigenic stimulation

Mycoplasma meleagridis-induced lesions in the tarsometatarsal joints of turkey embryos

Mycoplasma meleagridis (MM) has the ability to cause bone deformity in turkey poults. However, few pathological lesions have been described and no evidence of MM-induced damage to the bones has been shown. In this study, 17-day-old turkey embryos were inoculated with MM into the allantoic cavity. On the 27th day, eight of the 22 embryos presented with curved toes. Scanning electron microscopy of the tarsometatarsal joints showed fissures in the cartilage. Histological sections of the joints revealed only the infiltration of cells with eosinophilic granules. Immunohistochemical staining (IHS) showed the presence of MM in the aggregates of the bone marrow cells and the cells with eosinophilic granules. Some of these cells were harvested by laser capture microdissection (LCM), lysed, and used as template DNA. With a pair of MM-specific primers in a conventional polymerase chain reaction (PCR), a gene product was amplified, and it comigrated with the MM DNA, which indicates that these captured cells contained MM DNA. Thus, this research shows that inoculation of MM into the turkey embryos produced joint lesions and caused cellular infiltration within the bones.

Eosinophilia in duck embryos induced by an apathogenic strain of duck enteritis virus

An apathogenic strain of duck enteritis virus was injected into the allantoic cavity of duck embryos at 17 or 18 days of incubation. Four to 6 days later, the embryos showed massive infiltration of eosinophilic granulocytes in the spleen. Peroxidase and immunohistochemical labelling showed that the granulocytes were peroxidase-positive and contained major basic protein, and were most likely eosinophils. UltraIstructural examination of the eosinophils demonstrated granules of various sizes and shapes, and granules within the granules. Electron microscopy also showed that splenic macrophages were capable of phagocytosis, indicating that duck embryos, even at 23-24 days of incubation, were capable of responding to infection.

Elicitation of delayed type hypersensitivity in chicks after in ovo sensitization with different molecular forms of the same hapten

Lymphocyte sensitization, which participates in delayed type hypersensitivity (DTH) in chick embryos, was studied. The in ovo injection of dinitrophenylated keyhole limpet hemocyanin (DNP-KLH) or DNP-dextran (DNP-D) led to delayed onset of the hapten-specific reaction as shown by allergic contact dermatitis (ACD) after hatching. The extent of the ACD response was not directly dependent on the antigen dosage or the number of injections given for sensitizing. The magnitude of the ACD response was higher in chicks sensitized with DNP-D than in those given DNP-KLH. These findings suggest the presence of embryonic lymphocytes which can be sensitized by in ovo antigenic stimulation at the later stage of embryogenesis and may make possible the differentiation of functional lymphocytes. Antigen stimulation with higher doses may be inadequate for the in ovo sensitization of embryonic lymphocytes. The ACD response elicited by DNFB in chicks primed with either DNP-KLH or DNP-D was thought to be T-cell dependent, from the kinetics of the ACD peak within a period of 24 to 48 hr. Furthermore the conditions for in ovo sensitization of embryonic lymphocytes by DNP-D seem to be different from those for sensitization by DNP-KLH.

Ontogeny of lymphocytes expressing J chain in chickens

The ontogeny of chicken lymphocytes expressing J chain (LEJ) was investigated in the embryonic bursa of Fabricius, the spleen, and the thymus. Simultaneous appearance of LEJ was detected in the bursa and spleen on Day 14 of incubation. These cells were detected later in the thymus. The LEJ were found to increase rapidly in the spleen from the 19th to 20th incubation day. In adult chickens, the highest percentage of LEJ was also found in the spleen. These cells were seen in the thymus at a lower frequency. Intermediate numbers were found in bursal and peripheral blood lymphocytes. The frequencies of the LEJ were similar to those of lymphocytes positive for cytoplasmic immunoglobulins (Ig) IgA and IgM, but were not related to the number of lymphocytes expressing surface Ig. It is possible to consider that the suitable site for LEJ is the spleen, on the basis of the rapid increase in the number of LEJ just before hatching and from the fact that the highest value is found in adult chickens. Furthermore, LEJ may participate in secretion of IgA or IgM but not be associated with the expression of surface Ig.