Recent questions tagged immunology

Description : Briefly , describe about the foreignness of a molecule, which makes a substance antigenic?

Last Answer : To be antigenic macromolecules must come from foreign source. Antigens from related species are less antigenic than that of unrelated species. More distance the antigen source the better is the antigenesity. ... good antigens in animals, where as duck serum proteins are not good antigens for chick.

Description : Briefly describe about dosage and route of administration , which make a substance antigenic.

Last Answer : Combination of optical dosage and routes of administration will induce a peak immune response in a given animal. An insufficient dose will not stimulate an immune response. An excessive dose ... it causes a state of immunological unresponsiveness or non-response known as immunological tolerance.

Description : What is an antigen and antibody interaction ?

Last Answer : Antigen-antibody interaction is similar to an enzyme substrate interaction. The reaction between antigen and antibody occurs in two stages. Primary stage is the initial interaction of antigen-antibody ... as precipitation, lysis of cells, neutralization of toxins and fixation of compliments etc.

Description : Give some general features of antigen-antibody interaction ?

Last Answer : The reaction is specific and antigen combines only with its corresponding antibody and vice versa. Entire molecules react but not the fragment. There is no denaturation of antigen or ... reactions. Antigens and antibodies can combine in various proportions unlike chemicals with fixed valancy.

Description : What is antigenic specificity ?

Last Answer : Antigen antibody reaction is specific and specificity is determined by special configuration of antigenic determine.

Description : What is an epitope ?

Last Answer : The smallest unit of antigenesity is known as antigenic determinant or epitope. The part of the antigen at which the antibody reacts is known as epitope or antigenic determinant. It is a small ... of sensitizing on immuno site and of reacting with its complimentary site on the specific antibody.

Description : What is a paratope ?

Last Answer : The portion of the antibody molecule that binds to the epitope is called as paratope. Epitope and paratope determine the specificity of immunological reactions.

Description : What are the forces that are responsible for antigen-antibody reactions ?

Last Answer : The process that holds antigen-antibody together is called non-specific interactions. Inter molecular forces may be classified into four- Electrostatic bonds Hydrogen bonds Hydrophobic interactions Vander Val interactions

Description : Explain in brief about electrostatic bonds in antigen-antibody interaction ?

Last Answer : These are formed due to the attraction between opposite charged protein side chains.

Description : Explain in brief about hydrogen bonds antigen-antibody interaction ?

Last Answer : Reversible hydrogen bonds are formed between hydrophilic groups such as hydroxyl, amino and carboxylic group. Although hydrogen bonds are relatively weak, they play an important role in interaction of antigen-antibody.

Description : Explain in brief about hydrophobic interactions in antigen-antibody interaction ?

Last Answer : Contribute up to 50% of the total strength of antigen- antibody interactions. These reactions are found when ever the side chains of non-polar amino acids of antigen-antibody come together.

Description : Explain in brief about Vander Val interactions in antigen-antibody interaction ?

Last Answer : Temporary transfer of electrons from one molecule to another will result in the force of attraction between them. This is seen when the interacting molecules come close to each other.

Description : What is affinity of an antibody ?

Last Answer : The strength of binding of an antibody to a monovalent antigen or single antigenic determinant is called affinity of an antibody.

Description : What is avidity ?

Last Answer : The capacity of an antiserum containing various antibodies to combine with the whole antigen is called avidity. Thus, avidity is used to denote the overall capacity of an antibody to ... this is injected into the blood each antigenic determinant stimulate the production of particular antibody.

Description : What is a cross-reaction ?

Last Answer : Antigen-antibody reactions are specific, but in some cases antibody elicited by one antigen can cross react with another antigen. This reaction is called as cross-reaction and the antigen that produces ... is due to the presence of two or more antigenic determinants on the related antigen.

Description : Give an example of cross-reaction ?

Last Answer : Cross reactivity is often observed in polysaccharide antigens that contain similar oligosaccharide residue. A, B, O blood group antigens - These are glycoprotein expressed on RBC.

Description : What are heterophile antigens ?

Last Answer : Heterophile antigens are polysaccharides, which are structurally similar because of their limited complexity. They are derived from members of widely separated taxonomic groups.

Description : What is horseman antigen ?

Last Answer : The glycolipid antigens are present in most tissues of guinea pigs but not in the RBC. They are found in gastrointestinal mucosa in some people. This horseman antigen will not induce antibody formation.

Description : Into how many types is antigen-antibody reactions are broadly classified ?

Last Answer : It is broadly classified into five- Precipitation Agglutination Complement fixation Immunoassay using labeled reagents Immunohistrochemistry (Immunoflourescence)

Description : Briefly describe about precipitation reaction ?

Last Answer : When a soluble antigen combines with corresponding antibody in the presence of electrolyte at a suitable temperature and pH, the antigen-antibody complex forms an insoluble precipitate .Antibodies that form precipitate ate called precipitants.

Description : Give the mechanism of precipitation ?

Last Answer : Marrak proposed the lattice hypothesis to explain the mechanism of precipitation. The amount of precipitate formed is greatly influenced by relative proportions of antigens and antibodies. The valency of ... optimal concentration, the precipitation is complete. So that, large lattice is formed.

Description : What are the three distinct phases that a precipitation shows ?

Last Answer : The three distinct phases are Ascending part called ‘zone of antibody excess’. A peak called ‘zone of equivalence’. A descending part called ‘zone of antigen excess’.

Description : What is zone of antibody excess ?

Last Answer : In this, the first available antigen is completely filled by antibody molecules. Hence, no antigenic determinant is left out free. Unreacted antibody is seen in large amount, hence poor lattice formation.

Description : What is zone of equivalence ?

Last Answer : In this, ratio of antigen-antibody is seen optimal which results in large multimolecular lattice, hence maximum precipitation is observed.

Description : What are the applications of precipitation reactions ?

Last Answer : Precipitation reaction is the basic reaction for a number of techniques. It is less sensitive for detecting antibodies. Precipitation reactions in gels have several advantages rather than in liquid medium. They have forensic application in identification of blood and seminal stains.

Description : What are immuno diffusion reactions ?

Last Answer : These reactions can be used to determine relative concentrations of antigens and antibodies to compare antigens and to determine the relative purity of an antigen. They are mainly preformed in 1% agarose gels.

Description : Name the two-immuno diffusion techniques ?

Last Answer : • Radial immuno diffusion method and • Double immuno diffusion in two dimensions

Description : What is radial immuno diffusion method ?

Last Answer : It is used to qualitate the antigen. Suitable dilution of antiserum is incorporated in the agar gel. Antigen is added to the wells cut on the surface of the gel. As the antigen diffuses ... of known concentration of antigen, the concentration of antigen in the given sample can be determined.

Description : What is the limitation for radial immuno diffusion method ?

Last Answer : This method cannot the antigens present in concentration below 5-10 micro grams/ml.

Description : What is double immuno diffusion method ?

Last Answer : In this method, both antigens and antibodies diffuse radically from wells towards each other by establishing a concentration gradient. As equivalence is reached, a visible line of precipitation is observed. ... line of identity with the common epitope and a curved spur with the unique epitope.

Description : What is immuno electrophoresis ?

Last Answer : The resolving power of immuno diffusion was greatly enhanced bye immuno electrophoresis. This involves the electrophoretic separation of antigen into its constituent proteins followed by immuno diffusion. ... The formation of precipitin bands can be observed for the individual antigen components.

Description : How is immuno electrophoresis more advance than paper electrophoresis ?

Last Answer : In paper electrophoresis, serum proteins can be separated into 5 different bands but the same protein using immuno electrophoresis can be separated into 30 different proteins.

Description : Give some applications of immuno electrophoresis ?

Last Answer : This technique is useful for testing normal and abnormal proteins in serum and urine. It is useful to determine whether a patient produces abnormally a low amount of one or more proteins. It is also used if a patient over produces some serum proteins.

Description : What is counter current immuno electrophoresis ?

Last Answer : This technique involves the simultaneous electrophoresis of antigen and antibody in the gel in the opposite direction resulting in precipitation of point where there is optimum concentration of antigen- ... 30 minutes and is 10 times more sensitive than the standard double diffusion technique.

Description : What is immuno fluorescence ?

Last Answer : Fluorescence is the property of absorbing light ray of particular wavelength and emitting rays in different wavelength. Antigens that are bound to cells or tissue sections can be visualized by tugging the antibody molecule with a fluorescent dye or fluorochrome.

Description : What are the most commonly used fluorescent dyes ?

Last Answer : The most commonly used fluorescent dyes are fluorescin or rhodamine. Both dyes can be conjugated to Fc region of antibody without affecting the specificity of the antigen.

Description : Into how many types is immuno fluorescence is divided ?

Last Answer : Immuno fluorescence is divided into 2 types- Direct immuno fluorescence Indirect immuno fluorescence

Description : What is direct immuno fluorescence ?

Last Answer : In this method, the species antibodies are primary antibodies, which are directly conjugated to fluorescent dye.

Description : What is the disadvantage of direct immuno fluorescence ?

Last Answer : A separate fluorescent conjugate have to be prepared against each antigen to be tested.

Description : What is indirect immuno fluorescence ?

Last Answer : In a method the primary unlabelled antibody is detected with a number of reagents have been developed for indirect staining. The most common is fluorescence labeled anti isotype antibody such as fluoroscin labeled goat- mouse antibody.

Description : What are the advantages of indirect immuno fluorescence ?

Last Answer : The primary does not need to be conjugated with label. It increases the sensitivity of staining because multiple fluorochrome reagents will bind to each antibody molecule. This method has great flexibility.

Description : What are the uses of indirect immuno fluorescence ?

Last Answer : For identifying bacterial species Detecting antigen-antibody complexes in autoimmune diseases Detecting compliment components in tissues. Localizing hormones

Description : What is the full form of ELISA ?

Last Answer : Enzyme Linked Immuno Sorbant Assay.

Description : What is the basic principle of ELISA ?

Last Answer : The basic principle is an enzyme conjugated to n antibody reacts with a colorless substrate to generate a colored product.

Description : Name two enzymes that have been employed for ELISA ?

Last Answer : Alkaline, phosphatase, horseradish, preoxidase Para nitro phenyl phosphatase

Description : What is the significance of ELISA ?

Last Answer : It is used for the detection and for identification of either antigen or antibody.

Description : In how many ways ELISA can be carried out ?

Last Answer : It can be carried out in three ways. Indirect ELISA Sand witch ELISA Competitive ELISA

Description : What is the significance of indirect ELISA ?

Last Answer : It is used for the detection of the presence of serum antibodies against immuno deficiency virus (HIV, the causative agent of AIDS).

Description : What are the enzymes used for labeling of antibodies ?

Last Answer : Enzymes used for labeling of antibodies are horseradish peroxidase, alkaline phosphatase, ?- galactosidase, lacto preoxidase, etc.

Description : What is western blotting ?

Last Answer : Identification of specific protein in a complex mixture of proteins can be accomplished bye a technique that is known as western blotting.