Antibodies (Immunoglobulins- Igs) are Secreted by B Cells

Receptor in the immune system that "fits" the antigenic determinant Antigens (Nonself) Antigen: Any substance capable of exciting the immune system and provoking an immune response Examples of common antigens Foreign proteins Nucleic acids Large carbohydrates Some lipids Pollen grains Microorganisms Antigenic determinants: substances on the surface of antigens to which the immune system actually responds Antigens Antigens The basis of recognition or specificity of foreign cells or particles resides in the three dimensional geometry of the pathogen's surface. In bacteria or viruses, this would include the glycoproteins and glycolipids extending from the plasma membrane, short folded peptide chains extending from a viral protein coat. Even pollen grains and large toxic molecules work. These three dimensional shapes on the surface of invaders are antigenic, that is, they stimulate an immune response. Such molecular groups on an invader are known as antigens. Of course, our own cells contain thousands to millions of glycoprotein and glycolipid groups extending from their plasma membranes which also are antigenic. However, these self-antigens do not invoke a response in normal individuals because the body takes great pains in "educating" the immune system as to what antigenic geometries belong to the host. Small molecules are generally not antigenic because there is not enough surface to mount a specific response to. However, when attached to larger molecules, like proteins in our own body, these incomplete antigens (or haptens) do become antigenic. Chemicals that act as haptens and attach to our own proteins to invoke a response include urushiol (poison ivy toxin), animal dander, certain drugs, hair dyes, cosmetics, and other products. Antigen Receptor in the immune system that "fits" the antigenic determinant

Antibodies Bind to Antigens Very Specifically

Antibody Binding and Enzyme Substrate Colored product

Sharing Bodily Fluids - Unprotected Sex Write down your Tube Number (e.g. # 6) . That is your “name”. As you meet up and have “sex” with another individual, write down the number of that individual. Divide your Body Fluid Sample into two equal volume tubes and label the second tube with your number. This will be used later if a confirmation test is needed. Pipet your whole sample into a another person’s tube (e.g. #14) and mix. Then share out this mixed volume between between you and that person. The tube now has 6 and 14 (written 6-14). Pipet your whole sample into a second person’s tube (e.g. #4) and mix. Then share out this mixed volume between you and that person. The fluid is now 6-14-4. Pipet your whole sample into a third person’s tube (e.g. # 21) and mix. Then share out this mixed volume between you and that person. The fluid combo is now 6-14-4-21.

ELISA Protocol- 4 individuals come together for testing Get together in groups of 4 to do testing on your particular bodily fluids. You will be testing three samples of your fluids to be sure the results are predictable. Transfer 3 drops of your Combined Body Fluids to each of 3 wells. Three other people will also fill 3 wells of their own fluids. Transfer 2 drops of Positive control to each of 3 wells per group of 4. Transfer 2 drops of Negative control to each of 3 wells per group of 4. Let plate site for 5’ (to allow for antigen binding to wells) Shake off the fluid onto paper towel Add washing solution and shake off 3 times for all wells (to get rid of unbound antigen. Skipping this step may produce a false positive) Add 2 drops of antibody solution to all wells Let plate sit for 5’ (to allow for antibody binding to antigen) Add washing solution and shake off 3 times for all wells (to get rid of unbound antibody. Skipping this step could cause a false positive.) Add enzyme substrate to all wells (the Color reagent solution) Let site for 5’ before reading the plate (to allow for enzyme - if present - to react with substrate and produce color. If reagent with substrate is spoiled, could get a false negative)

Results Figure out which wells tested positive. Did the controls react as expected? If not, your results may not be trusted. Your instructor can guide you as to the “correct” results if you get anomalous readings. Write your results on the board, along with who you shared with, in order (e.g 6-14-4-21, where you are the first number in the grouping (the #6)) Determine which individual was originally infected.

Analyzing Results 1-5-16-8 - 2-5-13-26 + 3-13-9-17 4-1-7-25 5-12-9-15 6-4-12-5 7-4-26-8 8-9-13-3 9-5-15-6 10-17-2-26 11-12-7-25 12-6-11-1 13-14-9-2 14-15-6-11 15-7-10-12 Which number is present in all combinations that were positive? Why don’t all the numbers in an infective combination don’t themselves test positive? E.g., if 8 is infected and 3 has sex in the following order: 3-6-8-4, why won’t number 6 test positive too (assuming no other contact with an infected party)?