Multiple layers of protection Ch 43 Our Immune system Highly sophisticated Multiple layers of protection Millions of disease-specific cells that clone and defend us from sickness and death
We are born with certain protections and we acquire others during life 3 lines of defense against disease: 1. Innate protection: skin, mucus membranes severe pH’s enzymes phagocytes
2nd line: inflammation Skin breached Non-self cells targeted Phagocytes Non-specific Histamines incr blood flow Chemokines attract phagocytes
Interferons a, b are pt of innate defense They’re juxtacrine chemical messengers, telling neighbors to produce defensive enzymes against pathogens. Complement systems: serum proteins activated by non-self substances (lyse pathogens)
Non-specific Killer cells include macrophages, neutrophils, dendritic cells Natural Killer… Always on patrol for non-self cells. Pathogens’ ability to mask presence reduced by interferons.
The lymphatic system circulates many of the substances that fight infections
Acquired Immunity- defense against specific pathogens Function of lymphocytes (B or T) Recognize antigen molecules “designer destroyers”, ie, they’re specific
WHAT IS AN ANTIGEN? A substance that produces an immune response in an(other) organism An antigen’s epitope
Lymphocytes are either B or T type. Both have antigen receptors rooted to their cell membranes B’s are ‘Y’-shaped, made of 4 polypeptide chains Have Variable and Constant sections Every B cells’ is different
The B lymphocyte antigen receptor
T lymphocyte antigen recept’s Always attach to cells that they are defending against 2 straight PP chains (not 4), with variable tips Can recognize antigen fragments on the Cl 1 MHC ( major histocompatability complex) molecule common on most cells
Kill cells infected w/pathogens, cancer cells, transplants... Cytotoxic T cells (CD8’s) recognize antigens displayed by Class 1 MHC molecules. Kill cells infected w/pathogens, cancer cells, transplants... Major histocompatability complexes APC = antigen presenting cell CD 4. 8 are proteins
Class II MHC are found on phagocytes (antigen presenting cells) MHC2 present antigen fragments to Helper T cells which connect using CH4 molecules, then communicate to B cells to produce antibodies.
MHC molecules’ importance Genetics has most allelic diversity of all phenotypes. SO… Everyone but identical twins has unique heterozygous genotype for MHC markers. Everyone’s V & J segments can be rearranged
Humoral immune responses attack infections outside of infected host cells. Helper T cells read MHC class 2 displays on APC’s with the CD4 protein. Release cytokine messengers to B’s, wh produce plasma cells wh prod antibodies. These attack pathogens in plasma, lymph.
B & T lymphocytes perform a specific immune response in +,- 2 wks The primary immune response: Recognition of a specific infection, ending in antibody production that eliminates said pathogen.
5 types of immunoglobulins (antibodies) igM: pentomers. Causes agglutination igA: Dimers. From mucus membranes. Agglutinizing. In breast milk. igD: Monomers on ‘naïve’ (not-yet specialized) B cells. igG: Monomers, in blood, can pass to fetus giving it passive immunity. igE: Monomers, from mast cells. Triggers allergic rxns. What’s that spell!? MADGE
Active immunity; from getting the disease or being immunized Passive immunity is receiving the antibodies only. Temporary Remember these??? What ‘er U lookin at!?
Smallpox vaccinations Eradicated! CDC & VECTOR
Immunology and the Rh factor If an Rh – mother has an Rh + fetus: Mother may develop memory immunity (sensitivity) to child’s Rh protein. A subsequent Rh+ fetus could be attacked by Mom’s immune system
Organ transplants Allergens as antigens: igE triggers mast cells to release histamines Anaphylactic shock = loss of blood P MS: T’s attack CNS Type 1 Diabetes: attack pancreas SCID; severe combined immune def. AIDS attaches to the CD4 molec on the TH cells