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Immunology Interview Questions and Answers


This page contains the collection of Immunology Interview Questions and Answers / Frequently Asked Questions (FAQs) under category Medical. These questions are collected from various resources like informative websites, forums, blogs, discussion boards including MSDN and Wikipedia. These listed questions can surely help in preparing for Immunology interview or job.

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Give the classification of hypersensitivity?
Hypersensitivity is classified into five types-

► 1. Anaphylaxis
► 2. Antibody dependant cytotoxicity
► 3. Immune complex mediated diseases
► 4. Delayed type �o� cell mediated hypersensitivity
► 5. Stimulatory hypersensitivity

What is anaphylaxis?
It is most rapid hypersensitive reaction. It responds within minutes of applying a stimulus and can get localize. Reactions are mediated by release of pharmacologically active substances.

What is hypersensitivity?
The inflammatory response produced by inflammatory molecules result in tissue damage and some times even death. We call this as hypersensitivity or allergy.

What is delayed hypersensitivity?
We can recognize the Symptoms only days after exposure. This is delayed hypersensitivity (DTH).

What is a myeloma protein?
It is a monoclonal immunoglobulin produced from a myeloma cell.

What is opsonin?
Opsonin is a substance, which promotes phagocytosis of antigens by binding to them.

What is an incomplete antibody?
Antibody can bind to an antigen but cannot induce agglutination is called incomplete antibody.

What are iccosomes?
The particles coated with immune complexes and are released from follicular dendritic cell extensions, are called as iccosomes.

Name the scientists who classified hypersensitivity.
Coombs and Gell

What are hypersensitive reactions?
If humoral or cellular immunity is switch on to high for length of time, tissue damage may occur. Such reactions are called hypersensitive reactions.

What is auto immunity?
Disease caused by immunological reaction to self-antigen. Such type of diseases is classified either organ specific or non-organ specific.

Name some of the immuno suppressive agents.
► Cytotoxic agents such as chlorambucil, cyclophosphamide, and azathioprine
► Glucocorticoids
► Cyclosporine
► Antilymphocyte antibodies

What is immuno suppression?
Immuno suppression is particularly given to the patients who are undergoing organ transplantation in the treatment of autoimmunity, graft rejection and in allergy conditions.

What are the types in adjuvants?
► 1. Organic adjuvants
► 2. Synthetic adjuvants
► 3. Tuftsin

What is an adjuvant?
Adjuvant potentates the immune response Vaccines need to be enhanced by some substances, these substances are called adjuvants.

What is vaccination?
Vaccination means exploiting the immune system to protect against infectious diseases. Vaccination is done to protect against lethal diseases such as mumps, rubella, poliomyelitis, diphtheria, tetanus, small pox etc.

What is attenuation?
Natural behavior of an organism without causing disease is called attenuation i.e. reducing pathogenesity of the organism.

What is secondary immune response?
Secondary immune response occurs when second exposure to the same antigen occurs after weeks, months or after years.

What is inductive or latent period?
After immunogen is introduced no antibody is detected, this is latent or inductive period. In this period, immunogen is recognized as a foreign substance.

What is primary immune response?
First exposure to an antigen produces primary immune response.

What is a binder?
The binding protein (usually antibody) which binds to the ligand is called as binder.

What is an analyte or ligand?
The substance whose concentration is to be determined is called as an analyte or ligand.

What is importance of radio immuno assay?
It is the most sensitive technique used for detecting antigen or antibody. This type of reaction is also called as binder ligand assay.

In radio immuno assay what is the used to label an antigen?
In this technique, the antigen is generally labeled with a- emitting isotopes such as I125.

What is radio immuno assay?
It is a competitive binding assay in which fixed amount of antibody and radiolabelled antigen react in the presence of unlabelled antigen.

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

What are the enzymes used for labeling of antibodies?
Enzymes used for labeling of antibodies are horseradish peroxidase, alkaline phosphatase, �- galactosidase, lacto preoxidase, etc.

What is the significance of indirect ELISA?
It is used for the detection of the presence of serum antibodies against immuno deficiency virus (HIV, the causative agent of AIDS).

In how many ways ELISA can be carried out.
It can be carried out in three ways.
Indirect ELISA
Sand witch ELISA
Competitive ELISA

What is the significance of ELISA?
It is used for the detection and for identification of either antigen or antibody.

Name two enzymes that have been employed for ELISA.
1. Alkaline, phosphatase, horseradish, preoxidase
2. Para nitro phenyl phosphatase

What is the basic principle of ELISA?
The basic principle is an enzyme conjugated to n antibody reacts with a colorless substrate to generate a colored product.

What is the full form of ELISA?
Enzyme Linked Immuno Sorbant Assay.

What are the uses of indirect immuno fluorescence?
1. For identifying bacterial species
2. Detecting antigen-antibody complexes in autoimmune diseases
3. Detecting compliment components in tissues.
4. Localizing hormones

What are the advantages of indirect immuno fluorescence?
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.

What is indirect immuno fluorescence?
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.

What is the disadvantage of direct immuno fluorescence?
A separate fluorescent conjugate have to be prepared against each antigen to be tested.

What is direct immuno fluorescence?
In this method, the species antibodies are primary antibodies, which are directly conjugated to fluorescent dye.

Into how many types is immuno fluorescence is divided?
Immuno fluorescence is divided into 2 types-

1. Direct immuno fluorescence
2. Indirect immuno fluorescence

What are the most commonly used fluorescent dyes?
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.

What is immuno fluorescence?
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.

Give application of counter current immuno electrophoresis
This technique is applied to detect the antibody against hepatitis-B and to detect antibodies against SLE (systemic leupus erythromotosis) and used to detect specific antigen foe- meningo coccus in cerebrospinal fluid.

What is counter current immuno electrophoresis?
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-antibody.

This method produces visible precipitin with in 30 minutes and is 10 times more sensitive than the standard double diffusion technique.

Give some applications of immuno electrophoresis.
1. This technique is useful for testing normal and abnormal proteins in serum and urine.
2. It is useful to determine whether a patient produces abnormally a low amount of one or more proteins.
3. It is also used if a patient over produces some serum proteins.

How is immuno electrophoresis more advance than paper electrophoresis?
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.

What is immuno electrophoresis?
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.

This technique is performed on 1% agarose gel. Antigen mixture is first electrophori zed and separated based on charge, troughs are then cut in the agarose gel, and antiserum is added to the troughs.

The agarose gel is then incubated 18-24hrs during which the antigen and antibody diffuse towards each other. The formation of precipitin bands can be observed for the individual antigen components.

What is double immuno diffusion method?
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.

The patterns of precipitin lines that are formed when two different antigens are placed in adjacent wells indicate whether they share any common epitope or not.

Identity occurs when two antigens share identical epitopes; hence, the line of precipitation formed by them will fuse to give single curve line of identity.

Non-identity occurs when two antigens are unrelated. The antiserum form independent precipitin lines that cross each other.

Partial identity occurs when two antigens share common epitope. The antiserum forms line of identity with the common epitope and a curved spur with the unique epitope.

What is the limitation for radial immuno diffusion method?
This method cannot the antigens present in concentration below 5-10 micro grams/ml.

What is radial immuno diffusion method?
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 into the agar region, equivalence is established and ring of precipitation is formed. The area of precipitin ring is directly proportional to the concentration of antigen. By comparing the area of precipitin with a standard curve obtained by measuring the precipitin area of known concentration of antigen, the concentration of antigen in the given sample can be determined.

Name the two-immuno diffusion techniques.
► Radial immuno diffusion method and
► Double immuno diffusion in two dimensions

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