The Importance of Chickens in Immunological Research

The study of chicken immunology has become increasingly significant as chickens are the world’s main source of meat. Because they are known to spread many infectious diseases, it is important to understand the host-pathogen relationship in order to prevent the transfer of zoonotic pathogens from poultry to humans as well as the development of therapeutic agents.

Chickens and mammals have very similar immune responses to pathogens. We typically study mammals, such as mice and rats, to understand more about the immune system, but chickens can also be a key model for studying immunology. Even though their anatomy – organs and cells – is very different from mammals, chickens possess the same branches of the immune response: adaptive and innate.

Adaptive immunity allows the body to defend itself in a targeted way against harmful agents such as viruses and bacteria. Under adaptive immunity, there are two types of responses, humoral and cell mediated. Humoral immunity is an antibody-mediated response, and B and T cells are important players within this immunity response.  Cell-mediated immunity is primarily driven by mature T cells, macrophages, and the release of cytokines in response to an antigen and does not depend on antibodies for its adaptive immune functions.

The Research Study

Dr. Hyun S. Lillehoj has been studying the immunobiology of host-pathogen interactions and immunogenetics for over 25 years. Dr. Lillehoj published a study in the Journal of Veterinary Immunology and Immunopathology that details how her laboratory developed antibody clones against chicken interleukin-2 receptor αlpha chain or better known as CD25.

Studying IL-2/ IL-2R has important implications for the human immune system, and the monoclonal antibody-based drugs that have been developed to inhibit the human IL-2R are now used to prevent immune rejection of tissue and organ transplants. The team hopes that their chicken IL-2R antibodies will also serve as immune reagents for poultry immunology.   

The most common way to produce monoclonal antibodies is from hybridoma cell lines. In this study, mice were immunized with the immunogen, purified chCD25 (chicken CD25) protein coupled with Gerbu adjuvant. In order to produce the hybridomas, mice were euthanized, and spleen lymphocytes (B-cells) were fused with myeloma cells. The cell culture was later screened for any monoclonal antibodies binding to chCD25. The team produced fifty-four hybridomas, of which two clones, 32 and 54, were of interest.

A few experiments were carried out to validate chicken monoclonal antibody clones 32 and 54, to confirm that they detect chCD25. First, flow cytometry was used to analyze the cells within the broiler chickens. This method demonstrated that the two clones were able to bind to the surface of the CHO cells that were transfected with the gene sequence of chicken CD25 and other immune cells in the chicken, such as HD11 and HTC. Additionally, immunofluorescence showed that the antibodies have high specificity for cells in the spleen, bursa of Fabricius, and intestinal duodenum of the chicken. Finally, western blot showed that two monoclonal antibodies targeted the specific protein, chCD25 in the spleen, and identified a 55 kDa molecular band.

The study showed that the monoclonal antibodies against chCD25 do inhibit IL-2-dependent proliferation of chicken spleen cells and demonstrated that the antibodies against chCD25 are effective.

The clones against chicken interleukin-2 receptor αlpha chain developed in this study are available for researchers worldwide in the Kerafast catalog. Dr. Lillehoj’s complete collection of chicken antibodies are listed here. Other related reagents you might be interested in include: