Host Defenses: Specific Immunity & Immunizations
Describe how the third line of defense is different than the other two.
-acquired and specific
-only works after an infection or vaccine
-specificity & memory
List the 4 stages of a specific immune response.
-lymphocyte development and differentiation
-the presentation of antigens
-the challenge of B & T cells by antigens
-B cells and the production and activities of antibodies
-T cell responses
Discuss four major immune functions of cell markers.
-attachment to nonself or foreign markers
-binding to cell surface receptors that indicate self (i.e. MHC molecules)
-receiving and transmitting chemical messages to coordinate the response
-aiding in cellular development
Describe the major histocompatibility complex in two sentences.
(MHC) is a set of genes that code for human cell receptors and gives rise to a series of glycoproteins found on all cells except RBCs. They also allow the presentation of antigen to T-Lymphocytes (both CD-4 and CD-8 cells).
Contrast the way T cells recognize antigen with the way B cells do.
-B cells have receptors that bind all antigens
-T cells have receptors that only bind to processed antigens (antigens that have been presented by APC)
Summarize the maturation process of both B cells and T cells.
Both are produced in the bone marrow
-B cells mature in bone marrow
-T cells mature in the thymus
Mature B cells will travel to the Cortical Region of the Lymph Nodes to await activation. Mature T cells will travel to the Paracortical region (interior to the cortical region) of the Lymph Nodes to await activation
Outline the processes of clonal selection and expansion.
During the Antigen Independent period, stem cells produce many immature lymphocytes which get receptors specific to antigens. Clones that respond to self antigens (autoantigens) are eliminated during “clonal deletion”. From the “repertoire” of lymphocytes (each responding to a different antigen) a single clone which responds to a particular antigen will be activated and will proliferate (make many copies) and differentiate (make different subsets of cells)
Describe the B-cell receptor and the T-cell receptor.
-T cells have two subunits which each include a variable region which extends out of the cell membrane and a constant region which anchors the receptors to the cell membrane.
-B cells express a Y shaped antibody (immunoglobulin) that binds to antigens, and MHC-I and MHC-II markers.
-any substance that causes your body to react with an immune response
-any substance that induces a state of sensitivity or resistance after processing by the immune system
-the part of an antigen that defines its specificity and triggers the immune response
List characteristics of antigens that optimize their immunogenicity.
-Shape or type of molecule – usually a protein or having some peptide sequence
-Size - 10,000 Da (or amu) or greater
-Foreign – microbes, plant molecules, foreign human molecules (ie. different blood types or
cells with the wrong MHC-I molecule), or animal cells are considered foreign
-Accessibility - processed and presented antigens are more immunogenic than non-processed and presented antigens. Your immune system is alerting the lymphocytes about antigens.
List the types of cells that can act as antigen-presenting cells (APCs).
Diagram the steps in the B cell response.
1. binding of antigen
2. antigen processing and presentation
3. B cell/T(h) cell cooperation and recognition
4. B cell activation
6. clonal expansion
Make a detailed drawing of an antibody molecule.
Explain the six antibody functions.
1.Opsinizaiton: encourage the uptake of the microbe by phagocytes
2.Neutrilization: antibody fill the surface receptors on a virus to prevent it from attaching normally
3.Agglutination: the consequence of cross-linking cells or particles into large clumps
4.precipitation: clumping equal amounts of soluble antigen and antibodies making an insoluble precipitate (increases phagocytosis
5.Tag Antigens for destruction (increases phagocytosis
6.Complement: hole punch
Describe the memory response.
memory cells retain the memory of the infx so that if the infx ever happens again, these cells immediately begins to clone itself so that the infx does not spread.
List the three major types of cells that T cells will differentiate into after stimulation.
-T(H)1: CD4, requires MHC-II for activation
-T(H)2: CD4, requires B cells for activation
-T(C):CD8, requires MHC-I for activation
Explain how TC cells kill other cells.
-Macrophages/Dendritic cells engulf, process, and present antigen on their MHC-I molecules -Virally infected cells present viral antigens in their MHC-I molecules
-CD-8 cells and their T-cell receptors recognize that the MHC-I molecule (a self receptor – like your ID badge or Driver’s license) is either missing (like a cancer cell), is altered (like a virally infected cell), or is wrong (like a foreign human or animal cell) and bind to the cell presenting the antigen.
-CD-8 cells produce cytokins (cytotoxins, perforins, or granzymes) which create holes in the membrane and the cell lyses/dies.
List and define the four different descriptors of specific immune states.
-active: exposed to antigens
-passive: exposed to antibodies
-natural: involves natural biological process
-artificial: involves medical intervention
Discuss the qualities of an effective vaccine.
-low level of adverse SE
-should protect against natural exposure to antigen
-should stimulate both B/T cell response
-should have long term effects
-should not require numerous doses or boosters
-should be inexpensive and easy to administer
Name the two major categories of vaccines and then the subcategories under each.
-whole cells or viruses:
a. live, attenuated cells or viruses
b. killed cells or inactivated viruses
-part-of-organism preparations (subunits)
a. subunits derived from cultures of cells or viruses
b. subunits chemically synthesized
c. subunits manufactured via genetic engineering
d. subunits conjugated w/proteins (conjugated vaccines)
Discuss the pros and cons of killed (or inactivated) vs. attenuated vaccines.
inactivated vaccines are safer if less effective than attenuated vaccines
Describe the principle behind DNA vaccines.
Combining the genes for the antigens with a plasmid and either inserting the plasmid or inserting a yeast cell containing the plasmid into the patient. Production of antigen by the cells or yeast cells containing the plasmid will cause stimulation of an active immune response creating memory cells and antibodies to the antigen
Explain the principle of herd immunity.
collective immunity through mass immunization confers indirect protection on the nonimmune members
____ is acquired when a mother passes antibodies across the placenta to the fetus.
natural passive immunity
When antibodies clump whole cells together which type of antigen-antibody reaction occurs?
Which generation of vaccine is an acellular vaccine, such as the DTaP vaccine?
What is immunity through mass immunization indirectly protecting nonimmune members?
Which type of cells interact with the MHC class I molecules?
Which type of cells interact with the MHC class II molecules?
What type of cells contain the CD8 marker on their cell surface?
cytotoxic T Cells
____ directly kill virally infected cells and cancer cells by pumping them full of perforin, granzyme, and other toxins?
Which specific cells produce antibodies?
Which specific cell is most important for helping B cells to proliferate and differentiate?
T-Helper 2 cells