A monoclonal antibody, TcR2, has been shown to recognize an avian homologue of the mammalian alpha/beta T cell receptor (TcR). The TcR2-reactive molecule was found to be a T3-associated heterodimer with relative molecular mass of 90-kDa consisting of disulfide-linked 50-kDa and 40-kDa polypeptides. The sizes of the deglycosylated TcR2 polypeptides differed from those of TcR1, an avian homologue of the mammalian gamma/delta T cell receptor. Immunofluorescence analysis revealed that TcR1 and TcR2 are expressed on separate populations of T cells during their development first in the thymus and then in the periphery. Ontogenetic studies revealed that the TcR1+ thymocytes are generated first and the generation of TcR2+ cells begins approximately 3 days later. While most TcR2+ cells in the thymus expressed both CT4 and CT8, TcR2+ cells in blood and the spleen were either CT4+ or CT8+. The TcR1+ cells in blood and thymus were CT4-CT8-, but the majority of TcR1+ cells in the spleen surprisingly expressed the CT8 marker. The data suggest that TcR1 and TcR2 cells are generated in the thymus as separate T cell sublineages.

The avian embryo and its accessibility in the egg offer significant advantages for the analysis of immune system development. The separate developmental pathways ofthymus-dependent T cells and bursa-dependent B cells (1-4) and their derivation from hemopoietic stem cells (SC)' (5-7) were first disclosed in studies of chick development. Chick-quail chimeras were used to show that blood-borne stem cells periodically migrate into the thymus in response to chemoattractants produced by thymic epithelial cells (8, 9). The first wave of stem cell influx into the thymus begins on the fifth day of embryonic development (E5) in the quail and on E6.5 in the chick, and this influx persists for 1-2 d. At least two additional waves of stem cells enter the embryonic thymus after nonreceptive intervals of ti4 d (9, 10).The development of mAbs with specificity for the chicken TCRs and associated cell surface molecules (CD3, CD4, CD8) has allowed detailed study of the T cell progeny of hemopoietic stem cells (11-18). Sequential development of three sublines of daughter T cells has been defined using these antibodies. The first consists of T cells expressing the avian TCR-y/b homologue in association with the avian CD3 protein complex (13). These TCR1/CD3-bearing cells appear first in the E12 thymus .T cells expressing the avian a/a receptor complex, TCR2/CD3, appear on E15 (14-16).As in mammals, the immature TCR2 cells express both CD4 and CD8 molecules, whereas the TCR1 thymocytes express neither. A third T cell sublineage has recently been identified as cells expressing a different receptor complex (17, 18). These TCR3/CD3+ cells begin to appear in the thymus on E18.The present experiments, using chick-quail chimeras constructed by embryonic thymus engraftment, were primarily designed to examine lineage relationships among the different waves of stem cells and their intrathymic progeny. Specifically, we sought

Summary Antibody titers achieved by the immunization of hens are presented with examples. The transfer of immunoglobulins from the blood or oviduct to the egg and the distribution of these proteins in the various compartments which develop in the egg during incubation are quantitatively recorded. Possible procedures for extracting IgG antibody from the yolk are pointed out. Results concerning acid and temperature resistance of yolk antibodies are presented. An overview of the literature concerning with diagnostic use of yolk antibodies is given. The possible therapeutic application of egg antibodies is discussed. Zusammenfassung Das Hühnerei als Antikörperquelle Die durch die Immunisierung von Hühnern erzielten Antikörpertiter werden beispielhaft dargestellt. Der Transfer der Immunglobuline aus der Blutbahn bzw. dem Legeapparat in das Ei und die nachfolgende Umverteilung dieser Proteine in die sich während der Inkubation bildenden Eikompartimente werden quantitativ erfaßt. Die Möglichkeiten der IgG‐Antikörper‐Extraktion aus dem Dotter werden aufgezeigt. Ergebnisse zur Säure‐ und Temperatur‐Resistenz der Dotterantikörper werden vorgelegt. Eine Literaturübersicht bezüglich des Einsatzes von Dotterantikörpern wird gegeben. Der mögliche therapeutische Einsatz von Ei‐Antikörpern wird erörtert.

No abstract

A monoclonal antibody, mAb6, was produced that specifically bound to chicken T lymphocytes. Immunofluorescence analysis using a fluorescence-activated cell sorter revealed that the antibody reacted with approximately 50% of blood lymphocytes and with approximately 40% of splenocytes and thymocytes. It did not react with bursal cells and erythrocytes. Among different types of hemopoietic cell lines, only a T cell line was reactive with mAb6. When coupled to Sepharose 4B beads, mAb6 was found to be highly mitogenic for chicken T cells. In soluble form, mAb6 inhibited concanavalin A-induced T cell proliferation and the cytotoxic activity of allosensitized T cells, the inhibition occurring in a dose-dependent manner for both assays. Thus, the tissue distribution and the effects of this antibody on T cell responses suggest that mAb6 recognizes a T cell receptor present on a large proportion of chicken T cells.