Development And Antigen Presentation Of Dendritic Cell In Chicks Lungs

The basic process of immune response includes interaction,reaction and effective stages,where those three sages involve lymphocytes,antigen-presenting cells,and some cell factors for regulation.Currently,most studies on the immune function of poultry are based on the number of lymphoid cells,cytokines,and antibody tests,with very limited research on antigen-presenting cells(APCs).Dendritic cells(DC),known as the most powerful antigen-presenting cell,whose developmental condition in the body directly determines the strength of the immune function.Lungs contact outside air directly,bronchus associated lymphoid tissue(BALT)and mucosal immunity form the first line of defense against pathogen invasion.Further understanding of the development of DC in poultry lungs and related immune mechanism of lungs is of great importance.The present test was divided into two parts.In the first part,1day(d),4d,7d,10 d,14d and 21 d and 28 d,7 time-point groups were selected as the research objects.The number and distribution of DC in the lungs of each group was determined by flow cytometry and immunohistochemical staining methods.Expression levels of CCR6 and CCR7 in chicken lungs,as well as the development and migration of DC in the lungs were detected by qRT-PCR.In the second part,1d,4d,7d,14 d 21d,and 28 d old chicken are studied respectively.Immuned Newcastle disease vaccine(NDV)was used to stimulate chicken in each group,double staining was used to detect the number and distribution of DC and NDV in the lungs at 6h,12 h,24h,4d and 7d after immunization of each day-age group.DC strength of antigen of stress reaction in chicken lungs,and the development of DC antigen-presenting function at different time point are further studied.The result of flow cytometry and immunohistochemical analysis showed DC first appeared in the chicken lungs at one-day-old,and increased with age,proportion kept increasing and peaked in 7-14 days;DCs began to first appear in the medial wall of the three-stage bronchial airway,followed by BALT,and other immune tissue development,which gathered in the BALT and a large number of proliferation,and gradually migrate to the lung interstitial and other non-lymphoid tissue parts.Real-time fluorescent quantitative PCR test indicated that the CCR6 expression in chicken lungs volume increased significantly during 7 to 14 days of age,and the peak was in 14 days of age.At the same time the CCR7 expression was reduced,with rapid growth in DCs quantity,and mainly for the immature dendritic cells(imDC)during the stage.CCR6 expression decreased,and the CCR7 expression increased after 14 days of age,which showed that the DCs quantity growth slows down,but imDC began to mature quickly at this stage.Immunohistochemical double staining showed the immunization of NDV has a significant impact on the proliferation of DCs in chickens,and the proliferation effect was the most significant in the 7th day group.After immunization,DC can rapidly move to the NDV and swallow it,with the highest phagocytosis time at the age of 14 days.In summary,this study examined changes of DC development and antigen presentation function in the lungs of chickens of different age,in terms of the quantitative ratio,distribution,cytokine expression level,and antigenic stimulating response,which serves as reference for the further study of poultry DC and development,timely immunization,disease prevention,and treatment of poultry.