VIII - Immunology of the Cat

Abstract

This chapter focuses on the immune system of cats and the source of reagents available. The lymphoid organs of cats are classified as either central or peripheral. The central lymphoid organs are the thymus and the bone marrow, which are identified as the areas of lymphocyte development and differentiation. Lymph nodes, tonsils, spleen, and Peyer's patches of the gut are classified as the peripheral lymphoid organs. They are used as a platform for lymphoid cells that have achieved immune capability to come into contact with antigens. The feline thymus is an elongated multilobed structure located in the thoracic mediastinum. Each thymic lobule is clearly divided into an outer cortex region and an inner medulla. The main function of the lymph node is to filter the lymph and shift out foreign antigenic material. The node consists of a capsule, a cortex region, and a medulla. The size, cellular density, and composition of the lymph node change during the lifespan of a cat. This is mostly because of antigen stimulation and consecutive enhanced “trapping” of circulating lymphocytes followed by a transient shutdown in the exit rate of lymphocytes. The main function of the spleen is vascular filtration of foreign material and removal of damaged or aged erythrocytes.