Function of immune system - Defense

Immunity 1. Function of immune system Defense against “invasion” Integument (skin) Specialized cells Produce antibodies that act against foreign proteins = antigens Skin – first line of defense organ in the body  Components and function 3 – layers (epidermis, dermis, subcutaneous layer  Barrier  Chemicals (oils, sweat) acidic and lysozymes   Largest Other External Surfaces  Two  other routes of entry Respiratory tract  Mucus  Cilia  Digestive tract  Acidic  Saliva (Lysozymes) A. Challenge  latent period  primary response (accumulation of antibodies) B. 2nd challenge leads to secondary response - antibodies imprinted in "memory" cells and can be produced in greater numbers to combat antigen 2. Basic mechanisms 3. Secondary response A. WBC's ingest antigen-antibody complex & become macrophages 3. Secondary response (cont.) B. Macrophages go to lymph nodes 1. Stimulate lymph nodes to produce plasma cells which produce antibodies  Also release interleukin-I which causes nervous system to raise body temperature 2. Memory cells remain for subsequent exposures 4. Additional components of immunity A. Macrophages - ingest bacteria B. Neutrophils - release chemicals that neutralize antigen and kill themselves C. B Cells - encounter antigen in blood stream and divide to make plasma cells which produce antibodies 4. Additional components of D. Natural killer cells - kill cancer cells or cells infected by microbes such as viruses by puncturing cell, water rushes in & burst cell immunity (cont.) Additional components of immunity (cont.) E. T Cells - arise in bone marrow and migrate to thymus  4 kinds of T cells 1. Helper T Cells - detect infection and initiate T and B Cell responses. 2. Inducer T Cells - cause inactive T cells to mature. Additional components of immunity (cont.) 3. Cytotoxic T Cells - Recruited by Helper T cells and produce lymphokines that kill other cells involved in tissue rejection 4. Suppressor T Cells - terminate the immune response Players in the Immune Response  "Self" markers - identify the cells of an individual as their own.  Other individuals have their own MHC’s that are different and act as antigens to others  All under genetic control -Important in tissue transplants 5.Major Histocompatibility Complex Proteins (MHC) -  A. Four protein chains - 2 identical "light" chains and 2 identical "heavy" chains 6. Antibody Structure 7. How do we make so many different kinds of antibodies?  A. Instructional theory - each antigen elicits an appropriate recognition to be made during protein synthesis  B. Clonal selection theory - millions of different stem cells present in bone marrow and antigen initiates an appropriate type to be made in large numbers - cloned and produce more of antibody producing cells The Clonal Antibody Model Disorders of the Immune Response 1. Autoimmune Disorders - failure to recognize MHC's A. Rheumatoid arthritis B. Lupus C. Rheumatic fever A. Allergens recognized by antibodies which then bind to allergen and cause inflammation at site. B. Produce histamines which cause dilation of blood vessels and leaky capillaries. C. Results in redness and swelling localized - hives  general - anaphylaxis  2. Allergies 1. Caused by a retrovirus - injects its genetic material into a cell and cell makes more virus particles AIDS A. HIV virus - human immunodeficiency virus B. HIV virus attacks macrophages and inducer and helper T cells C. Infected cells die after releasing progeny viruses. ALL inducer and helper T cells eventually destroyed. D. Produces a protein that suppresses T-Cell recognition of the virus - protease treatment AIDS E. HIV virus may block transcription of MHC proteins that protect T cells from "self" recognition F. Body loses ability to: Recognize and destroy cancer cells Mount the immune response against infection G. Death does not result from the HIV virus  the lack of response by T Cells to infection At the end of 2004, the CDC estimates that 415,193 people were living with AIDS in the USA Of these, 35% were white 43% were black 20% were Hispanic 1% were of other race/ethnicity. Of the adults and adolescents with AIDS in the US, 77% were men. Of these men, 58% were men who had sex with men (MSM) 21% were injection drug users (IDU) 11% were exposed through heterosexual contact 8% were both MSM and IDU. Of the 93,566 adult and adolescent women with AIDS in the US, 64% were exposed through heterosexual contact 34% were exposed through injection drug use. An estimated 3,927 children were living with AIDS at the end of 2004, of whom 97% probably acquired the infection from their mothers. •The number of deaths among people with AIDS in the US remained relatively stable in the period 1999-2003, before dropping slightly to an estimated 15,798 deaths in 2004. •Since the beginning of the epidemic, an estimated 529,113 people with AIDS have died in the USA.  During 2004 there were an estimated 48 pediatric AIDS diagnoses in the US, compared to 190 in 1999 and 823 in 1994. The decline in pediatric AIDS incidence is associated with more HIV testing of pregnant women and the use of zidovudine (AZT) by HIV-infected pregnant women and their newborn infants.  The age group 35-44 years accounted for 39% of all AIDS cases diagnosed in 2004 in the US. Nearly three-quarters of all people who have died with AIDS did not live to the age of 45.  More than 25 million people have died of AIDS since 1981 worldwide.  Africa has 12 million AIDS orphans.  By December 2005 women accounted for 46% of all adults living with HIV worldwide, and for 57% in sub-Saharan Africa.  Young people (15-24 years old) account for half of all new HIV infections worldwide more than 6,000 become infected with HIV every day.  Of the 6.5 million people in developing and transitional countries who need life-saving AIDS drugs, only 1 million are receiving them.