Immunology and Plasmids Flashcards
What is the definition of an antigen?
a foreign material typically a protein that elicits an immune response so we can have specific recognition
What is the first line of defense?
Innate; skin to prevent entry, mucous membranes and their secretions (e.g. lysozymes) to prevent colonization; normal microflora to act as competition for nutrients; all non-specific
What is the second line of defense?
Natural killer cells and phagocytes; inflammation; fever (creates non-optimal environment, also helps immune cells to divide faster); antimicrobial substances; still non-specific
What is the third line of defense?
Adaptive (acquired immunity); specialized lymphocytes (T cells and B cells); antibodies
Describe the general characteristics of antibodies
Y-shaped molecule where each “prong” bind single, identical epitopes; composed of a light chain and heavy chain (V and C components, where C is elongated in the heavy chain but the V components remain the same size)
What are the different kinds of antibodies?
IgM (antibody, secreted first during immune response; snowflake shaped), IgG (main antibody involved in the immune resposne; single Y-shape), IgA (secreted antibody, two Y’s attached at the Fc), IgD (“dispensible”–does not seem to be essential), and IgE (involved in the allergic reaction…“evil”)
What are the characteristics of IgG?
Monomer, therefore bivalent, most abundant Ab (~80%), recruits immune system, can also be secreted like IgA, is present in the lymph, blood, and intestine, can cross the placental barrier, enhances phagocytosis; neutralizes toxins and virsuses; protects the fetus and newborn; half life of 23 days;
Random deletions of V, D, and J genes in the light and heavy chains create unique antibodies–no change in the C chain?; subsequent mutations of the already-created antibodies refine the existing ones
meh
What is the B-cell clonal selection theory?
Test 1: if the cell makes self-antigen binding antibodies, kill it
Test 2: if the cell makes antibodies which are useful in fighting the infection, stimulate it to divide to proliferate the antibodies
What are the forms of B cells and where do they come form?
Plasma B cells (protein factory–pump out the antibodies into circulation) and memory B cells (divide slowly and do not make as many antibodies; useful for long-term immunity); they come from naive B cells that are activated to germinate upon antigen exposure
Remember that when you are first infected with an antigen, your body will produce IgM Ab in small amounts peaking at 10-11 days, but it will produce IgG antibodies in much larger amounts peaking at about 15 days; as infection is taken care of Ab titer decreases; when reinfected, body still makes new IgM Ab but memory cells are converted to plasma cells and a much larger IgG Ab titer is created (peaks within 7 days of the second infection, as does IgM)
ayyyy
What are the protective mechanisms of Ab joining to An in vivo?
Agglutination (antibodies bind the same antigen and clumps them together, reducing the number of infectious units to be dealt with); opsonization (coating An with Ab to enhance phagocytosis); neutralization (Ab blocks adhesion of virus and bacteria to mucosa and blocks the attachment/activity of toxins) ; activation of complement (builds pores into cell wall to causse cytoplasm to leak out); Ab-dependent cell-mediated cytotoxicity (used for fighting bigger antigens such as eukaryotes; Ab bind to target organisms and cause eosinohpils to release lytic enzymes to digest the organism)
What are secondary Ab?
Secondary antibodies bind to the primary antibody to assist in detection, sorting and purification of target antigens.
All mouse Ab specific for a certain Ag will have the same tail (crystallizable fragment, Fc) but will have different Ag binding sites due to random mutation
ye
How are Ab made in situ?
Lab animal (horse, hamster, mouse, rat, sheep, goat, chicken) are injected with a signle Ag (usually a protein, but may be a polysaccharide, hapten, etc) and will create Abs against it; serum is collected and Ab is purified; secondary Abs can be made from the Fc (secondary Abs specific for the Fc tail)
How are Abs collected from blood?
Blood from a lab animal is spun to precipitate cells down to the bottom; yellowish serum (plasma) is passed through affinity chromatography which binds the Fc region of Abs; elution occurs by a low pH (glycine, pH=2.4) and then neutralized in fractionation tube; samples are tested by SDS-Page to determine peak fraction
What are polyclonal Abs?
Polyclonal: all IgG are from different B cells
• Each antibody from a different B cell may bind a different epitope
○ Good, because if one epitope mutates, there may be several other sites that different antibodies can still bind to;
Immune reactions are polyclonal, which is beneficial because if one epitope mutates so the Abs from a B-cell no longer recognize it, the other B-cell Abs will still recognize their epitope and can fight the infection
What are monoclonal Abs?
Monoclonal: all from one B-cell, only bind one epitope
• Start off with a B cell and makes it so that it never dies
