Question

A microsope slide showing agglutination when blood is mixed with antisera. our red blood cells are much stronger antigens and large aggregated clumps will be readily visible when agglutination has occurred. If you have neither A nor B antigen on your red blood cells, you will have no agglutination of either antisera and therefore the cells are blood type 0. Figure 4 shows a picture of aggluti-nation when cells clump or aggregate. No agglutina-tion is a smooth suspension of cells and serum. To observe antigen-antibody reactions as demon-strated by agglutination reactions To observe the hemagglutination reaction of our red blood cells with type-specific antisera and determine our blood type To understand the importance of antibodies and the role they play in our immune system THE EXERCISE Part A: Latex Agglutination Testing MATERIALS: Group A and B antiserum to Streptococcus (PathoDx latex agglutination reagents) One known and one unknown Streptococcus on sheep blood agar plates (BA) Latex agglutination card Sterile applicator sticks PROCEDURE: Work in groups of two or three 1. Obtain a latex agglutination card, one BA plate with an unknown Streptococcus, and one BA plate with a known Streptococcus. Observe the type of hemolysis that each of your microorganisms exhibits, and from your previous knowledge of streptococci, speculate about the type of streptococcus your unknown might be. 3. Carefully pick 4 or 5 13-hemolytic colonies of your unknown microorganism with a sterile applicator stick and rub it onto a designated oval on the card. Repeat this step in another oval. 4. In a third oval, rub 4 or 5 colonies of your known organism with a sterile applicator stick. 5. Resuspend the latex reagents by gentle inversion. Add 1 drop of Strep A latex to the first oval and 1 drop of Strep B latex to the second oval. Add 1 drop of the specific antisera (A or B) to your known microorganism. 6. Mix the reagent and microorganism with an appli-cator stick, using a clean end for each oval. Hold the slide under good lighting and gently tilt the slide back and forth. A positive agglutination reaction with one of the latex reagents usually

Answer 1

1. serotype classsification is based on the ability of bacteria to react with a antiserum contains antibodies those are specific to the surface antigen structure of bacteria.streptococci posses specific carbohydrate antigens in streptococcal cell wall which is reacted with group of specific antibodies present inthe antisera.

2. known organism act as positive control, which means we know in which antisera spot (A or B) the reaction occurs.

3. antigen is present on the surface of cell wall of streptococcus which is isolated in liquid form and this will subjected to reaction with antisera.

4. immunoglobulins are other wise called serum antibodies present in the fluid portion of blood. blood plasma contains antibodies.

5. the type of antigen-antibody reaction is observed is agglutination reaction where the the surface antigens reacts with antibodies present in antisera forming clumps.

6. O group persons universal donars and the AB group persons are called universal acceptors. because the O group person red blood cell donot have antigens on their surface so he can donate blood to any individual since he does not have antigens the antibodies present in plasma of recepient cannot recognise the surface antigens.

in the same way the AB persons will not have antibodies in plasma so one can receive blood from any type of individual.