From the combination of knowledge and actions, someone can improve their skill and ability. It will lead them to live and work much better. This is why, the students, workers, or even employers should have reading habit for books. Any book will give certain knowledge to take all benefits. This is what this the interferon system tells you. It will add more knowledge of you to life and work better. Try it and prove it.

The Interferon System

The bursa of Fabricius and the thymus are "central lymphoid organs" in the chicken, essential to the ontogenetic development of adaptive immunity in that species. Surgical removal of one or both of these organs in the newly hatched chicken, followed by sublethal X-irradiation the next day, has permitted recognition of two morphologically distinct cell systems in the "peripheral lymphoid tissues" of the spleen, gut, and other organs, and clear definition of the separate functions of each cell system.

The thymus-dependent development is represented morphologically by the small lymphocytes of the circulation and the white pulp type of development in the tissues. As in mammals, the thymus-dependent tissues of the chicken are basic to the ontogenesis of cellular immunity: graft versus host reactions, responses of delayed hypersensitivity and homograft rejection; and play a less clearly defined role in the antibody response to at least some antigens. Thymectomized-irradiated chickens are deficient in all these responses, and grow more slowly than any of the other experimental groups. In these animals germinal centers, plasma cells, and capacity for immunoglobulin synthesis remain intact.

The bursa-dependent development is represented morphologically by the larger lymphocytes of the germinal centers and the plasma cells, and functionally by the immunoglobulins. Bursectomized-irradiated chickens are agammaglobulinemic and unable to produce detectable antibody despite intense, repeated stimulation with bovine serum albumin and Brucella abortus organisms. The thymus-dependent development in these animals seems to be normal; they have adequate numbers of lymphocytes in the circulation and tissues, are able to reject skin homografts, though more slowly than usual, and to exercise graft versus host reactions. The short life span of these chickens has precluded adequate study of responses of delayed hypersensitivity.

There was no evidence of significant impairment of reticuloendothelial function in either the bursectomized-irradiated or the thymectomized-irradiated group, as judged by the clearance of colloidal gold and I131-tagged keyhole limpet hemocyanin.

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The functions of the thymus system and the bursa system in the chicken

Introduction IN THE PAST 10 years there has been a significant increase in studies relating to the function of the immune system. The recent popularity of research in this area is due in part to the awareness by the medical and scientific community of the importance of immune function in the maintenance of a disease-free homeostasis, to technological advances in the field of immunological research, and to the increased availability of funds for investigation in this area. From the rapidly expanding literature in this field it has become increasingly apparent that the immune system interacts with most, if not all, of the body systems. One of the most intriguing of these interrelationships is that which occurs between the immune and reproductive systems and involves interactions of pituitary hormones, gonadal steroid hormones and thymic hormones. Because of the complexity of this area the present review will concentrate on only one aspect of the interaction between the two systems, namely the effects of gon...

Regulation of the Immune System by Sex Steroids

Effects of gender and sex steroids on the immune response

Publisher Summary This chapter discusses the intimate mechanisms of the regulation of antibody responses by T cells, the significance of these phenomena for the regulatory processes of the immune system, and their possible implication for the pathogenesis of various immunopathological states. The chapter adheres to popular terminology to refer to the two distinct classes of immunocompetent lymphocytes—T cells and B cells. The T cells are lymphocytes that have differentiated under the influence of the thymus and are responsible for mediating cellular immune reactions—such as delayed hypersensitivity and transplantation reactions. These cells participate in the development of humoral immunity but are not capable of secreting humoral antibodies. Because T cells stimulated by antigen respond by a clonal expansion and differentiation; and by being activated to perform their specific function, the former is elected as “educated T cells” and the latter as “activated T cells.” Activated T cells may result from stimulation by agents other than specific antigen. The B cells are lymphocytes that have differentiated under the influence of the bursa or its analog in mammals and ultimately become the effector cells in humoral immunity by the virtue of synthesizing and secreting immunoglobulin antibodies.

The regulatory influence of activated T cells on B cell responses to antigen.

0.63 mg. of 19-nortestosterone in 0.1 ml. of corn oil, when injected into the fertilized eggs of the white leghorn hybrid strain of chickens, “Wisco-white,” on the 5th day of incubation, completely inhibits the development of the bursa of Fabricius in both sexes. In the normal chick the bursal primordium appears as a proliferated epithelial mass dorso-caudal to the embryonal cloaca on the 5th day of incubation. By 168 hours of incubation it forms a tubular structure; its terminal end enlarges into a bursal vesicle on the 10th day and becomes lymphoidal by the 15th day. The bursa is fully formed and lymphoidal in 17- day old chick embryos. In 19-nortestosterone-treated embryos the bursal primordium becomes highly vacuolated. Later it remains as a convoluted, short duct without forming the bursal vesicle. Thus the hatched chicks arc bursaless. The secondary effects of this hormone on the rectal complex are the stunted growth of the ventral anal lip, increase of musculature in the dorsal lip and an attenuate...

Inhibition of the development of the bursa of Fabricius in the embryos of the common fowl by 19-nortestosterone.

Summary 1.Two strains of chickens were thymectomized and/or bursectomized at 1 to 3 days after hatching and skin homografts made at 4 or 6 days of age. 2.Thymectomy delayed skin homograft rejection, but neither steroidal or surgical bursectomy had any effect.

Effect of Thymectomy and Bursectomy on the Survival of Skin Homografts in Chickens

1. 1. Removal of the bursa of Fabricius at 1 day of age effectively prevents a large percentage of the animals from producing precipitins to bovine serum albumin (BSA) when inoculations are made to 20 weeks of age. Bursectomy at 10 days is less effective.

2. 2. Two steroid hormones, 19-nortestosterone and 17-ethyl-19-nortestosterone, administered on the 12th or 13th day of incubation, cause a 5- to 20-fold reduction in bursal weight. Correspondingly, precipitin production against BSA is grossly impaired. Spleen, thymus and body weights were not consistently affected.

Further Studies on the Role of the Bursa of Fabricius in Antibody Production

1. Thymectomy of chickens during the first 3 days of age does not consistently affect precipitin production to bovine serum albumin when challenged at 6 to 9 weeks of age. In some cases, thymectomized groups did not differ in mean peak titer from controls; in some cases the response was significantly lower; in one case the response was significantly higher. This variation was not evident for the time necessary to clear antigen from the circulation. 2. Of intact and sham control birds 100% responded by producing precipitins, whereas 6% of the thymectomized birds did not give a detectable response. This frequency of negative responders was statistically significant. 3. There was a tendency for groups with greater amounts of residual thymic tissue to give higher mean precipitin titers. However, the titers of birds with no residual thymus fell in a range very similar to that of the controls. 4. The development of natural hemagglutinins was not affected by thymectomy. 5. Splenectomy performed from 2 to 10 days of age significantly delayed the appearance of precipitins but did not affect the mean peak titer. 6. Bursectomy at 1 to 2 days of age reduced the mean peak precipitin titers and the natural hemagglutinin titers drastically. Most birds did not give a detectable response.

Richard L. Aspinall

Papers

Inhibition of the development of the bursa of Fabricius in the embryos of the common fowl by 19-nortestosterone.

Effect of Thymectomy and Bursectomy on the Survival of Skin Homografts in Chickens

Further Studies on the Role of the Bursa of Fabricius in Antibody Production

Effect of thymectomy and bursectomy on precipitin and natural hemagglutinin production in the chicken.

Effect of thymectomy and bursectomy on precipitin and natural hemagglutinin production in the chicken