In order to assess chicken T cell-mediated responses after immune stress, 200 two-week-old chickens were randomly divided into control group(C) and treatment groups (T 1 and T 2). The live I-type of Newcastle disease vaccine (ND) was taken as the source of immunological stress. The chickens in group (T 2) were injected with overdose of live I-type Newcastle disease vaccine. After vaccination, the dynamic changes of CD4 +, CD8 +T cells on thymus were detected by immunohisto-chemistry. The ultra-structure of T cells on thymus of the chickens in group (T 2) was observed by electron microscopic. The result showed: (1) After immune stress, from day 1 to day 5, the number of the CD4 +T cells significantly declined and reached the bottom at day 5, but the number of the CD8 +T cells increased dramatically and peaked at day 5. (2) After immune stress, from day 1 to day 5, part of T cells of chicken thymus came with apoptotic and pathological changes of putrescence continually. These results underscore: the immune stress can cause transient immune adjustment. These changes for chickens were the self-protection mechanism of immune system to adapt to survival and avoid immune disorder.
Vaccines, which could induce protective immunity while producing a minimal antagonistic response in the bird, play an increasing role in disease control of poultry [
Mixed sex, White Leghorn chickens were obtained from the chicken farm of ShanXi Agricultural University. All chickens were maintained in brooder cages with feed and water ad libitum. The chickens were randomly divided into control group (C) and treatment groups (T1 and T2). At 15 days-of-age, Chickens in group(C) were vaccinated with Saline. Chickens in group (T1) were normally vaccinated with the IV live I-type of Newcastle disease vaccine. Chickens in group (T2) were vaccinated five times live I-type Newcastle disease vaccine. After vaccination, on day 1, 3, 5, 10, 15, 21, five of birds from control group and treatment groups (T1 and T2) were caught to further test respectively.
The presence of CD4+, CD8+T cells was investigated in thymus using the avidin-biotin complex (ABC) method for immunohistochemistry [
The chickens were sacrificed by carotid. After the vaccination, at 8:00 am on the 1d, 3d, 5d, 10d, 15d, 21d, five chickens from every group were killed. Approximately 1 - 2 mm2 segments of thymus were extracted with cyclohexane-ethanol and embedded in Spurr’s epoxy resin. Sixty-ninety nanometers thick sections were cut with a diamond knife on a Reichert ultramicrotome and stained for 10 min with 1% KMnO4. Photographs were taken using a Zeiss 10C TEM operated at 80 kV and a Philips CM20 with FEG operating at 160 kV (resolution 0.1 nm).
There were many positive CD4+T cells in the cortex and medulla of thymus, especially in the medulla. On third day after vaccination, the numbers of CD4+T cells began to decline in groups (T1 and T2) compared with group (C). The numbers of CD4+T cells in groups (T1 and T2) were significantly lower than them in group (C) on fifth day (P < 0.05). There was no difference in the number of CD4+T cells between groups (T2) and group (C) on other days. But On fifteen day after vaccination, the numbers of CD4+T cells began to rise, the numbers of CD4+T cells in groups (T1) were significantly higher than them in group (C) (P < 0.05).
There were many positive CD8+T cells in the cortex and medulla of thymus, especially in the medulla. On third day after vaccination, the numbers of CD8+T cells began to rise in groups (T1 and T2) compared with group (C). The numbers of CD8+T cells in groups (T2) were significantly higher than them in group(C) on fifth day (P < 0.05). On tenth day after vaccination, the numbers of CD8+T cells began to decline, but the numbers of CD8+T cells in groups (T2) were significantly higher than them in control group on fifteen day (P < 0.05).
The heterochromatin of normal T cells nucleus distributed uniformly. There were more ribosomal particles in the cytoplasm (
Whether vaccination will trigger immune stress appears to depend on several factors, including the vaccine of the challenge to the immune system, acupuncture, capture, because the live I-type of Newcastle disease vaccine has moderate virulence, adding the role of acupuncture and capture the chicks. These are strong stresses for chicken [
Thymocyte developmental stages can readily be defined by the expression of the cell surface receptors CD4+ and CD8+. CD4+ and CD8+T cells maintain a state of equilibrium, as the foreign antigen stimulation [
The immune system should not be viewed as an autonomous entity, but rather as one component of an interactive network constituted by the immune, nervous, and endocrine systems. Various studies have focused on the relationships between GC and the development of T cells in the thymus. Due to an increase of GC, for the thymus, the observed involution could be associated with an increase of thymocyte apoptosis. To avoid the disorder of immune system, many T cells were induced apoptosis after immune stress. It may help immune response to clear the excess activated T cells thereby and maintain stability of immune response. At the same time, the immune stress caused the pathological changes of T cells [
It has been suggested that immune stress is immunosuppressive. Dhabhar and McEwen have argued that immunoenhancement by acute stress would be adaptive from an evolutionary stand point, and might be regarded as an integral component of the fight or flight response [
The study was supported by the Soft Science Foundation of Shanxi Province (2013041038-02) and Natural Science Foundation of Shanxi Normal University (ZK1301, YK1301). It was also supported by the Students Innovation Foundation of Shanxi Normal University (SD2013CXCY-82).