What is the role of the Harderian gland in poultry vaccination?

The Harderian gland plays a key role in poultry vaccination, as it is one of the most important mucosal lymphoid tissues (MALT) in the head of chickens.

🔹 Roles in vaccination:

1. Local immune stimulation site:

When the vaccine is administered as an eye drop or spray, vaccine particles enter through the eyes and nasal passages.

The Harderian gland, because it is full of lymphocytes and antibody-producing cells (especially IgA), is quickly stimulated and creates a local and general immune response.

2. Production of local antibodies (IgA):

These antibodies are secreted on the surface of the eyes, nose, and respiratory tract of the chicken and prevent the entry of viruses or bacteria.

3. Creating systemic (general) immunity:

In addition to local immunity, the Harderian gland can also enhance the production of antibodies in the blood (IgG and IgM) by stimulating the immune system.

4. Importance in live vaccines

✅ Summary: The Harderian gland acts like an "immunity factory" in chicken vaccination, and this is the main reason why live vaccines are often given in poultry farms in the form of eye drops or sprays.