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Immunolocalization for EM Using immunoglobulin molecules as tags for select proteins and carbohydrates. Visualized by using colloidal gold or enzyme reactions.

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Presentation on theme: "Immunolocalization for EM Using immunoglobulin molecules as tags for select proteins and carbohydrates. Visualized by using colloidal gold or enzyme reactions."— Presentation transcript:

1 Immunolocalization for EM Using immunoglobulin molecules as tags for select proteins and carbohydrates. Visualized by using colloidal gold or enzyme reactions Leishmania megasome labeled with 10nm gold

2 Immune Responses Humoral 1. Humoral: B lymphocytes produce antibodies recognizing an antigen from foreign substance. Antibodies are then secreted into blood stream.

3 Immune Responses Humoral 1. Humoral: B lymphocytes produce antibodies recognizing an antigen from foreign substance. Antibodies are then secreted into blood stream. Cell-mediated: 2. Cell-mediated: Mature T lymphocytes - antigen responding, response control, and response mediating cells

4 IgG Immunoglobins (Ig)

5 IgA IgG Immunoglobins (Ig)

6 IgAIgM IgG Immunoglobins (Ig)

7 Glossary Antibody Antibody (anti-foreign body) is a protein produced by a white cell (B lymphocyte).

8 Glossary Antigen Antigen (antibody generating substance) is any agent, such as a chemical or microorganism that is recognized by the antibody. Not all antigens are immunogens (e.g hapten).

9 Glossary Antibody Antibody (anti-foreign body) is a protein produced by a white cell (B lymphocyte). Antigen Antigen (antibody generating substance) is any agent, such as a chemical or microorganism that is recognized by the antibody. Not all antigens are immunogens (e.g hapten). Immunogen : Immunogen : Any substance to which an animal responds by making antibodies. All immunogens are antigens.

10 Glossary Antibody Antibody (anti-foreign body) is a protein produced by a white cell (B lymphocyte). Antigen Antigen (antibody generating substance) is any agent, such as a chemical or microorganism that is recognized by the antibody. Not all antigens are immunogens (e.g hapten). Immunogen : Immunogen : Any substance to which an animal responds by making antibodies. All immunogens are antigens. Antigen binding site Antigen binding site - relatively small region of an antibody that binds to the antigen.

11 Epitope Epitope (antigenic determinant) - is that part of an antigen that is recognized by a single antibody.

12 Hapten Hapten - low molecular weight compounds (such as plant hormones) that typically do not elicit a spontaneous immune response but can be recognized by antibodies. Typically attached to an immunogen.

13 Epitope Epitope (antigenic determinant) - is that part of an antigen that is recognized by a single antibody. Hapten Hapten - low molecular weight compounds (such as plant hormones) that typically do not elicit a spontaneous immune response but can be recognized by antibodies. Typically attached to an immunogen. Hybridoma Hybridoma - fusion product between B cell and myeloma cell (“immortal cell”).

14 Epitope Epitope (antigenic determinant) - is that part of an antigen that is recognized by a single antibody. Hapten Hapten - low molecular weight compounds (such as plant hormones) that typically do not elicit a spontaneous immune response but can be recognized by antibodies. Typically attached to an immunogen. Hybridoma Hybridoma - fusion product between B cell and myeloma cell (“immortal cell”). HAT selection HAT selection - culture media that contains hypoxanthine, aminopterin and thymadine. A selective media that only allows hybridomas to grow.

15 Terms used in Immunolabeling Primary antibody: Primary antibody: An antibody that is specific to the antigen of the sample to be localized. Can be conjugated to a signal (gold, fluorochrome or enzyme).

16 Terms used in Immunolabeling Primary antibody: Primary antibody: An antibody that is specific to the antigen of the sample to be localized. Can be conjugated to a signal (gold, fluorochrome or enzyme). Secondary antibody: Secondary antibody: An antibody that recognizes a primary antibody. Usually always is conjugated to signal.

17 Terms used in Immunolabeling Primary antibody: Primary antibody: An antibody that is specific to the antigen of the sample to be localized. Can be conjugated to a signal (gold, fluorochrome or enzyme). Secondary antibody: Secondary antibody: An antibody that recognizes a primary antibody. Usually always is conjugated to signal. Diluent Diluent: Physiologic buffer and non-specific protein (e.g. albumin or non-fat milk) used in diluting the antibodies. Sometimes detergent added to decrease surface tension of sections.

18 Block: Block: Physiologic buffer, high salt, and non-specific protein. The protein adheres to any “sticky” sites that might allow non-specific binding of antibodies.

19 Etching: Etching: treating resin sections with HCl or sodium borohydride to reduce steric hindrance or expose hidden antigenic sites.

20 Polyclonal: Antibodies are collected from sera of exposed animal, - or - monoclonal colonies a combination of monoclonal colonies is combined. Antibody Production

21 Polyclonal: Antibodies are collected from sera of exposed animal, - or - monoclonal colonies a combination of monoclonal colonies is combined. Rabbit, Goat, Horse, Rat, Sheep Can be any animal: Rabbit, Goat, Horse, Rat, Sheep, etc… Antibody Production

22 Polyclonal: Antibodies are collected from sera of exposed animal, - or - monoclonal colonies a combination of monoclonal colonies is combined. Rabbit, Goat, Horse, Rat, Sheep Can be any animal: Rabbit, Goat, Horse, Rat, Sheep, etc… Suite of antibodies recognizing multiple antigenic sites of injected biochemical. Antibody Production

23 Monoclonal: Individual B lymphocyte hybridoma is cloned and cultured. Secreted antibodies are collected from culture media.

24 Monoclonal: Individual B lymphocyte hybridoma is cloned and cultured. Secreted antibodies are collected from culture media. BALBc mice Typically BALBc mice Rat. Sometimes Rat (ascites fluid).

25 Monoclonal: Individual B lymphocyte hybridoma is cloned and cultured. Secreted antibodies are collected from culture media. BALBc mice Typically BALBc mice Rat. Sometimes Rat (ascites fluid). Antibodies recognize one antigenic binding site of the antigen.

26

27 Determining which B cell to clone ELISA or Immuno- fluorescence

28 Generic TEM Immunolabeling Protocol Fixation: Glutaraldehyde only Dehydration Embedding in methacrylate resin (e.g. LR White, Lowicryl, or Quetol) SectionImmunolabel Optional - Post-stain

29 Controls Adsorption - primary antibody exposed to excess of antigen to remove any labeling. Label without antibody - no antibody, shows labeling not due to reaction with label Omission of primary antibody - the secondary or tertiary antibodies should not recognize the tissue. Pre-immune sera - collected from animals that have not produced antibodies, or use “normal serum” from non-immunized animals of same species

30 Immunolabeling Sections - Float grids on blocking solution - Incubate in primary antibody - Wash thoroughly with buffer to remove unbound antibody

31 Incubate with secondary antibody or protein A/G Wash again to remove unbound secondary Last wash should be water.

32 Double Labeling Incubate sections with second primary antibody of interest

33 Incubate with secondary - different size gold Note steric hinderence at asterisk

34 10 nm and 5 nm gold

35 Microtubules labeled with anti-beta tubulin

36 How are the antibodies coupled to the gold? The proteins are attached to the gold particles by: a). Charge attraction (Lysine) b). Hydrophobic attraction (Tryptophan) and c). Sulfur binding (Cysteine and Methionine) Strongest binding suggested to be the sulfur "hinge" joining the the two F c regions

37 Using Protein A or Protein G instead of secondary antibody

38 Ferritin enhanced labelingSilver enhanced

39 Freeze fracture immunolabeled

40 Freeze fracture immunolabeled Negative stain Immunolabeled

41 Etching to expose antigenic sites


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