1a : the act or action of grasping with the intellect : understanding children who have difficulty with comprehension of spoken language What the artist actually needs is comprehension of his aims and ideals by men he respects â¦ â H. L. Menckenb : knowledge gained by comprehending tests that measure the students' comprehension in math She carried on ...
The inflammatory response (inflammation) occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause. The damaged cells release chemicals including histamine, bradykinin, and prostaglandins. These chemicals cause blood vessels to leak fluid into the tissues, causing swelling.
The cellular events that result in delayed hypersensitivity reactions primarily involve T cells and macrophages. First, local immune and inflammatory responses at the site of foreign antigen up-regulate endothelial cell adhesion molecule expression, promoting the accumulation of leukocytes at the tissue site.elayed hypersensitivity is a major mechanism of defense against various intracellular pathogens, including mycobacteria, fungi, and certain parasites, and it occurs in transplant rejection and tumor immunity. The central role of CD4 + T cells in delayed hypersensitivity is illustrated in patients with AIDS.