I M M U N I T Y
Innate (inborn) Immunity does not distinguish one pathogen from another Figure 14.2 Overview of Innate and Adaptive Immunity Our first line of defense includes physical and chemical barriers to infection, keeping microbes from invading. If these barriers are breached, the pathogen is met by a second set of defenses that includes components of both innate and adaptive immunity. Adaptive (learned) immunity mounts a different response against each new pathogen
Inflammation and Fever Caused by release of chemicals from your white blood cells (histamine from mast cells, and pyrogens from macrophages) Inflammation causes blood vessels in area to leak (allowing fluid and white blood cells into area) Fever is thought to inhibit growth of microbes
Adaptive (learned) immunity: a very specific defense Lymphocytes are white blood cells that launch a specific defense (two kinds of lymphocyte: B cells and T cells) They produce antibodies proteins that can recognize specific molecules as non-self and target them for destruction
Lymphocytes, Lymph, Nodes
Figure 14.1 Antigen-antibody interactions are specific B lymphocytes are covered with receptors that are specific for one type of foreign protein (antigen). If that antigen is encountered, as shown here on an invading bacterium, the lymphocyte is stimulated to mount a defense against the antigen-bearing invader.
Our Immune System and Vaccination The first time we are exposed to a foreign substance, our adaptive immune response is slow For subsequent exposures, we have a very rapid memory response so rapid, in fact, that we often don t experience any symptoms at all This is the basis for vaccination- to provide a first exposure (but one that doesn t make us sick!) Figure 14.3 Vaccination Vaccines are composed of microbial antigens, providing a non-harmful first exposure that primes your adaptive immune system for a rapid response upon subsequent exposure. What is in a vaccine?
If the memory response is long-lasting, why do we get a flu shot each year? During viral replication, mutations arise that may alter certain viral proteins. This is called antigenic drift. In some cases, the altered virus is no longer recognized by our antibodies (our memory response from a previous vaccination)
More on Blood donations! (the ABO and RH systems)
ABO blood group genetics The ABO gene encodes an enzyme that attaches sugars to the outside surface of Red Blood Cells Red blood cell phenotype Red blood cell genotype I A allele attaches type A sugars. I B allele attaches type B sugars. i allele is inactive. No sugars. Type A Sugar A Type B Sugar B I A I A or I A i I B I B or I B i Type AB Sugars A and B I A I B Type O ii 11
ABO Antibodies Your body produces antibodies against the sugars you DON T have on your red blood cells: Red blood cell phenotype Red blood cell genotype Type A Sugar A I A I A or I A i Type B Sugar B I B I B or I B i Type AB Sugars A and B I A I B Type O ii 12
Rh factor another type of RBC surface protein 2 alleles: + and + is completely dominant to - If your blood type is O negative, You are i i If your blood type is O positive. You can be i i + + or i i + The majority of people are Rh+ (ie. have at least one + allele).
Rh factor another type of RBC surface protein +/- alleles are dominant/recessive your blood type do you make Rh antibodies? Rh+ Rh- If you are Rh-, you make antibodies against the Rh+ antigen
Hemolytic disease of the newborn (HDN) Mother is Rh, fetus is Rh+ Mother s Rh+ antibodies can pass through placenta and attach to fetal blood cells
Hemolytic disease of the newborn (HDN) Can be treated by giving mom RhoGAM Hides fetal Rh+ antigen from mom s immune system so she won t mount a memory response
Allergic Reactions An adaptive immune response to something non-pathogenic Food allergies (nuts, shellfish, milk, eggs, fish) Asthma (cat hair, pollen, insect feces) Hay fever (pollen) Insect bites Anaphylaxis (drugs, peanuts, venoms) Massive inflammatory response that, in extreme cases, may be fatal
Autoimmune diseases When something goes wrong with the self vs. non-self distinction.. Figure 14.5 Multiple sclerosis is an autoimmune disorder Multiple Sclerosis (MS) -immune system attacks myelin cells that support nerves In multiple sclerosis, the patient s immune system attacks myelin, resulting in slower nerve transmission. Type 1 diabetes Immune system attacks cells of the pancreas Rheumatoid Arthritis: Psoriasis:
Antibody Production
Antibody therapies