Immunology Midterm 1

Clonal Selection: selection and activation of B and T lymphocytes by binding epitopes to BCR and TCR.
1. A single progenitor cell gives rise to a large number of lymphocytes, each with a different specificity. 2. Clonal deletion - removal of potentially self-reactive immature lymphocytes3. Pool of mature naive lymphocytes.4. Clonal Expansion - foreign molecule causes lymphocyte to become activated and divide to produce many identical progeny, each having the same antigen specificity.

All blood originates from hematopoietic stem cells in the bone marrow.1. Lymphoid lineage: gives rise to lymphocytes, which includes B, T, and Null cells.2. Myeloid lineage: gives rise to blood cells that travel to specific tissue, where they stay. These cells are part of the innate immune system. Includes macrophages, dendritic cells, neutro/eosino/basophils, mast cells.

1. 50-70%2. phagocyte against microorganisms3. able to survive in anaerobic conditions (inflamed/dying tissue)4. in circulation 7-10 hours, then migrate to tissue where they stay for a few days5. Myeloid lineage

1. 1-3%2. phagocytes against parasitic organisms; involved in allergic reactions3. Myeloid lineage

1. <1%2. function in inflammatory process3. Myeloid lineage

1. not blood cell, but produced in bone marrow2. function in inflammatory process3. Myeloid lineage

1. 0.1%2. Function: internalize foreign material, migrate to lymph nodes after internalizing and while digesting material, display pieces on surface (APC) while migrating. Activate Th and Tc cells.3. have long extensions of cell surface membrane.5. Myeloid lineage

1. 1-6%2. While circulating in blood they are monocytes, when they reach designated tissue they differentiate into macrophages.3. Phagocytes against microorganisms.4. Myeloid lineage.

Immature: have antibodies on their surface that are identicalMature: "plasma cells" have no antibodies on their surface, but secrete huge quantities of themPart of the adaptive immune system

T-Helper: recruit B cells and T-cytotoxic cellsT-cytotoxic cells: bind to an antigen-MHC complexMatures in thymus

5-10% of lymphocytesactivated by macrophages
use innate cell surface receptors to recognize and defend against tumor and infected cell surfaces.Mechanism of killing is the same as T-cell: signaling molecules to cell to induce apoptosisThree receptor molecules:1. lectin-like receptors2. killer immunoglobulin-like receptors3. Fc (CD16) receptors that bind to antibody and trigger ADCC

Contains hematopoietic and non-hematopoietic cells in a stroma, which is a fiber meshwork containing extracellular matrix molecules. The microenvironment provides signaling molecules that regulate the process (cytokine growth factors for survival, proliferation, differentiation, maturation of blood cells).

About 1% of total blood volume is composed to leukocytes, and, of this 1%, 20-40% are lymphocytes (ie, adaptive immune system) and 60-80% are cells belonging to the innate immune systems, such as neutro/baso/eosinophils, dendritic cells, and macrophages. Therefore, the immune system represents a small fraction of the total blood volume, and of that blood volume that is represented, more than half of it belongs to the innate immune system.

1. Neutrophils are 50-70% of the WBC, and belong to the granular class of white blood cells. Other cells belonging to this class are Eosinophils (1-3%), Basophils (<1%). Granular class are distinguished by dye affinity. Two types of granules: specific (specific content for cell function), and azurophillic (organelles)2. Lymphocytes are 20-40% of the WBC, and belong to the agranular class of white blood cells. Other cells belonging to this class are the monocytes/macrophages (1-6%). These have no noticeable granules.

T cells move from the cortex to the medulla region as they mature. There are other cells in the thymus that support this process.Major components: medulla, cortex, lobesFunction: Initial selection of T cells occurs here: eliminates 95-99% of T cells, which express affinity for self antigens. Most active early in life.