Pages 410-414 third line of defense Three important aspects: 1. It is antigen specific 2. It is systemic 3. It has memory © 2015 Pearson Education, Inc. Two Humoral immunity antibody-mediated immunity types of immunity: Provided by antibodies present in body fluids Cellular immunity cell-mediated immunity Targets virus-infected cells, cancer cells, and cells of foreign grafts © 2015 Pearson Education, Inc. Antigens (nonself) Any substance capable of mobilizing the immune system and provoking an immune response common antigens: Foreign proteins (strongest) Nucleic acids Large carbohydrates Some lipids Pollen grains Microorganisms © 2015 Pearson Education, Inc. Human cells have many surface proteins that our immune cells recognize This concept restricts transplant potential Another human’s cells can trigger an immune response because they are foreign Blood type is a great example as agglutination takes place with a mismatch © 2015 Pearson Education, Inc. Agglutination Reaction 19-6 Lymphocytes—respond to specific antigens: 1. B lymphocytes (B cells) T lymphocytes (T cells) 2. Antigen-presenting cells (APCs) Dendritic cells Macrophages B lymphocytes © 2015 Pearson Education, Inc. Arise from hemocytoblasts of bone marrow Become immunocompetent before they encounter the antigens they may attack © 2015 Pearson Education, Inc. T B cells develop immunocompetence in the thymus oversee cell-mediated immunity cells develop immunocompetence in bone marrow provide humoral immunity Both groups move to lymph nodes to await antigen encounters Haspi.org Engulf antigens Present fragments of antigen on their own surfaces T cells recognize these fragments T cells become activated T cells release chemicals called Cytokines which: enhance T cell activation Stimulate activity of other T cells Help to activate B cells and cytotoxic T cells © 2015 Pearson Education, Inc. Arise from monocytes in bone marrow phagocytize pathogens present parts of the antigens on their surfaces, for recognition by T cells remain fixed in the lymphoid organs Secrete cytokines © 2015 Pearson Education, Inc.