Chapter 43 Immune System

Leukocytes Cover dendritic cells

Basics Antibodies Antigen Looks for foreign antigen Specific to a single antigen Antigen Located on the surface of the cell/invader Multiple antigens on a single pathogen

Blood Example Rh factors Positive is dominant over Negative Erythroblastosis fetalis Occurs when mom is Rh – and baby is Rh + First child, not mixing of blood, so both are okay. But with second baby, mom will have antibodies that would attack baby’s blood. Used to be fatal, but now it can be dealt with O Neg is the universal donor, AB Pos is the universal acceptor TEST QUESTION

Lymphoid Organs/tissues – adenoids, tonsils, thymus, spleen, Peyer’s patches, appendix Lymphatic System

Immune system has to do three things 1. Recognize non-self Recognize foreign antigens/invaders and attack it 2. Remember non-self After destroying the foreign antigen/invader, you want to remember it just in case if it comes back. 3. Recognize self You need to know who is the “enemy” and who is a “friendly”; if your immune system attacks your own cells, that becomes and autoimmune disorder

Innate vs Adaptive immunity Barrier defenses: Skin – there are friendly bacteria on your skin that offer some protection Mucous membranes – only make mucous Secretions – sweat, tears, saliva (have lysozymes), etc. Internal defenses: Phagocytic cells – neutrophils, macrophages Natural killer cells – look for foreign antigens and cancer cells Antimicrobial proteins – interferons, complement proteins Inflammatory response – histamine, cytokines, mast cells, etc. (next slide) Fever- some fever is good to fight infection, but really high temp is not good because it can denature your proteins! Adaptive Immunity (later on in this presentation)

Inflammatory Response Histamines and cytokines (signaling molecules) released. Capillaries dilate (vasodilation- direct response to histamine) Neutrophils digest pathogens and cell debris. Tissue heals. Antimicrobial peptides enter tissue. Neutrophils are recruited.

Recognizing the enemy Toll-like receptors TLR5- recognizes flagellin (you don’t have flagellin so ATTACK) TLR4- lipopolysaccharides (component of bacteria, so you don’t have this, so ATTACK) TLR3- double-stranded RNA (foreign nucleic acids, so ATTACK)

Eating the enemy

Lymphocytes B cells made in bone marrow T cells made in thymus Have antigen (antibody generator) receptors which recognize epitopes of foreign antigens

Antigen receptors On B Cells Four chains- two heavy, two light C region (constant region) V region (variable region- makes each B cell different) When the antigen receptor is released, it becomes an antibody

Antigen Receptors on T Cells Similar to B cell receptor, but do NOT release their receptors

Making Antigen Receptors/antibodies 40 V genes X 5 J genes = Over 200 combinations!! Light chains and heavy chains also combine differently so even more combinations!

Self Markers MHC: major histocompatibility complex About 20 genes, 100 alleles On somatic cells Class I: found on all nucleated cells in the body Class II: found on cells in the immune system (macrophages, T cells, etc.) and is how they communicate with each other MHC are usually similar among people who are related to each other, but you can still find people that have similar MHCs who are not related to you (think about transplants or infertilities)

Humoral Response

What do the antibodies do? Plasma cells have more…. Ribosomes on the ROUGH ER

Immunoglobulins M- first one present on the scene G- most abundant, passes placenta A- in secretions, breastmilk E- allergies D

Helper T-Cells

Cell-mediated immunity Sees self and non-self

Activating B-Cells

Putting it together

Another one

Remember the Alamo… Memory cells! Booster shots make more memory cells

Passive vs Active Immunity Active – YOUR ANTIBODIES You got sick, you fought your own fight and made antibodies Or you got a vaccine, which helped prep your immune system just in case if the invader comes, but you still made your own antibodies Passive – NOT YOUR ANTIBODIES Breastmilk (think IgA) gets passed from mother to fetus Anti-venom, serums, antibody shots (like when you go overseas)

Autoimmune diseases More common in females than males (why? We don’t know) Rheumatoid Arthritis Connective tissue in joints and other organs (heart, lungs) is attacked Rheumatic heart disease Heart valves are attacked Untreated strep infection, body thinks heart valves are strep Lupus affect the joints, skin, kidneys, blood cells, brain, heart, and lungs Graves’ Disease Over-active thyroid gland SCID (Bubble Boy) Little or no immune system Allergies IgE; cross-linking triggers release of histamine Anaphylactic shock – severe allergic reaction, reduce blood flow to brain and heart HIV/AIDS Destroys helper T-cells You don’t die from HIV, you die from another infection because your immune system is compromised Test question- RHD