Inflammation and Immune Response

Inflammation

• Inflammation is a response to tissue damage or infection, characterized by swelling, pain, redness, warmth, and loss of function.
• It involves blood vessels dilating, capillary and venule permeability increasing, and tissue becoming red, swollen, warm, and painful.
• White blood cells invade the region, and pus may form as white blood cells, bacterial cells, and cellular debris accumulate.
• Body fluids seep into the area, and a clot containing threads of fibrin may form.

Inflammation Response

• Fibroblast appears, and a connective tissue sac may form around the injured tissues.
• Phagocytes are active, removing bacteria, dead cells, and other debris.
• Cells reproduce, and newly formed cells replace injured ones.

Phagocytosis

• Phagocytosis involves leukocytes called phagocytes, which engulf the antigen.
• Phagocytes include eosinophils, neutrophils, and monocytes, which develop into macrophages.
• During phagocytosis, phagocytes in capillaries first adhere to the inner walls of capillaries, then squeeze themselves across the pores in the capillary walls.
• Once macrophages develop in connective tissue, they are attracted to the injured tissue by histamine and crawl towards it using amoeboid motion.

B-Lymphocytes and Antibody Production

• B-lymphocytes are activated when they encounter an antigen that fits their antigen receptors, either alone or with helper T cells.
• Activated B cells proliferate, enlarge their clone, and differentiate into plasma cells, which secrete antibodies.
• Antibodies combine with antigen-bearing agents, helping to destroy them.

Antibody Structure and Function

• Antibodies are globular proteins called immunoglobulins (Ig).
• There are five classes of immunoglobulins: IgG, IgA, IgM, IgD, and IgE.
• Each class has a specific function, such as defending against bacterial cells, viruses, and toxins, or promoting allergic reactions.

Cytokines

• Cytokines are polypeptides synthesized and secreted by T cells that enhance certain cellular responses to antigens.
• Types of cytokines include colony-stimulating factors, interferons, interleukins, and tumor necrosis factor.
• Cytokines stimulate bone marrow to produce lymphocytes, block viral replication, stimulate macrophages to engulf viruses, and stimulate B cells to produce antibodies.

Immune Response to Viruses

• The immune response to viruses involves the activation of T cells, B cells, and cytokines.
• Cytokines, such as interferons, stimulate macrophages to engulf viruses and stimulate B cells to produce antibodies.

Acquired Immunity

• There are four types of acquired immunity: naturally acquired active immunity, artificially acquired active immunity, artificially acquired passive immunity, and naturally acquired passive immunity.
• Naturally acquired active immunity occurs when a person is exposed to live pathogens, and the immune system develops lymphocytes and antibodies, providing long-term resistance.
• Artificially acquired active immunity occurs when a person is injected with a vaccine composed of weakened or dead pathogens, and the immune system develops lymphocytes and antibodies, providing relatively long-term resistance.
• Artificially acquired passive immunity occurs when a person is injected with a vaccine composed of antibodies for a particular antigen, providing short-term resistance.
• Naturally acquired passive immunity occurs when a person receives antibodies from another person, such as a mother to a fetus, or during blood transfusion, providing short-term resistance.

Autoimmune Diseases

• Autoimmune diseases occur when the immune system fails to recognize "self" body cells, resulting in the activation of an immune response against one's own tissues.
• Examples of autoimmune diseases include myasthenia gravis, multiple sclerosis, rheumatoid arthritis, and scarlet fever.

Acquired Immunodeficiency Syndrome (AIDS)

• AIDS is caused by the Human Immunodeficiency Virus (HIV), which infects lymphocytes and suppresses immunity.
• HIV infects lymphocytes, particularly helper T cells, and some epithelial cells.
• AIDS was first discovered in homosexual male patients in Los Angeles and New York, who developed rare disorders like pneumocystis pneumonia and Kaposi's sarcoma.