Immunology

Immunology is the branch of biology that deals with the study of the immune system, its mechanism, types, and mode of action.

The immune system is the body’s defense mechanism that triggers response against any foreign particle that has not been previously encountered and helps to combat infections or diseases. The immune system that was present before the birth of a person is called the innate immune system and the system that learns as the person grows and becoming more efficient in recognizing the pathogens as time passes on, is the acquired immune system.

Immune cells have the capacity of the self, non-self discrimination. Tolerance to self-antigen and effector functions against foreign antigen either by the production of antibodies (humoral immunity) or by effector T cells (cell-mediated immunity) is the main function of immune cells.

Biomarkers: Definitions, Types, and Applications

Biomarkers: Definitions, Types, and Applications

Biomarkers are biological signals found in blood, other body fluids, and tissues that indicate a normal or abnormal condition, or disease.

Personalized Vaccines: the Next Big Step in Vaccinology

Personalized Vaccines: the Next Big Step in Vaccinology

A personalized vaccines has the potential to create the next golden age in the field of immunization and vaccinology.

Antibody Affinity vs. Antibody Avidity

Antibody Affinity vs. Antibody Avidity

Antibody affinity is a quantitative measure of binding strength whereas antibody avidity incorporates the affinity of multiple antigen-binding sites.

Adjuvants: Types and Functions

Adjuvants: Types and Functions

Adjuvants are ingredients used in some vaccines to enhance the immunogenicity of antigens (immunogens).

Epitopes: Types, Function, Epitope Spreading

Epitopes: Types, Function, Epitope Spreading

Epitopes are the immunologically active discrete sites on the antigen molecule that physically bind to antibodies, B-cell receptors, or T-cell receptors.

Cells of the Immune System

Cells of the Immune System

Immune system consists of many different cells, some of which acts as a part of innate immunity while lymphocytes are major players.

Immunoglobulin E (IgE) Antibodies: Structure, Functions

Immunoglobulin E (IgE) Antibodies: Structure, Functions

IgE is one of the five isotypes of human immunoglobulins and plays role in helminthic infestations and allergic reactions.

mRNA Vaccine: What it is and How it works?

mRNA Vaccine: What it is and How it works?

mRNA vaccines teach our cells how to make a protein. This protein triggers an immune response inside our bodies.

Radioimmunoassay: Principle, Uses, Limitations

Radioimmunoassay: Principle, Uses, Limitations

Radioimmunoassays are high sensitivity in vitro assay techniques to measure concentrations of antigens using specific antibodies.

Neutralization Test for Virus and Toxins

Neutralization Test for Virus and Toxins

When microbial toxins and specific antibodies combine and the active portion of the toxins are blocked, neutralization occurs.

Indirect Fluorescent Antibody (IFA) Test

Indirect Fluorescent Antibody (IFA) Test

Indirect fluorescent antibody test (IFA) is a semi-quantitative, sensitive, and rapid test to detect specific antibodies or antigens.

Phagocytosis: Mechanism and Steps

Phagocytosis: Mechanism and Steps

Phagocytosis is a process in which specialized cells engulf and digest extracellular pathogens. It is an important innate defense mechanism.

Isotypes, Allotypes, and Idiotypes

Isotypes, Allotypes, and Idiotypes

Based on the location of antigenic determinants sites, immunoglobulins are divided into, isotypes, allotypes, and idiotypes.

Immunoglobulin A (IgA): Structure, Functions

Immunoglobulin A (IgA): Structure, Functions

IgA is the second most abundant class of immunoglobulin. sIgA is a dimer and is confers mucosal immunity.

Immunoglobulins (Antibodies) Structure and Classes

Immunoglobulins (Antibodies) Structure and Classes

Antibodies are Y-shaped tetra-peptide molecules consisting 2H and 2 L chains. There are 5 classes of immunoglobulins IgG, IgA, IgM, IgE, and IgD.

Immunochromatography/ Lateral Flow Immunoassay: Principle and Uses

Immunochromatography/ Lateral Flow Immunoassay: Principle and Uses

Immunochromatography is a combination of chromatography and immunoassay to detect the presence of target analyte in a sample.

Herd Immunity: Types, Threshold, Usefulness

Herd Immunity: Types, Threshold, Usefulness

When most of a population is immune to an infectious disease, this provides indirect protection to those who are not immune to disease.

Serotypes and Their Significance

Serotypes and Their Significance

Serotyping is the classic tools for epidemiological study of organisms having multiple serotypes: E. coli, Salmonella, Vibrio, Shigella, S. pneumoniae.

Direct Fluorescent Antibody (DFA) test

Direct Fluorescent Antibody (DFA) test

Direct fluorescent antibody (DFA) test detects the presence of a particular antigen using a fluorescently labeled monoclonal antibodies (mAb).

Antigens in disease diagnosis

Antigens in disease diagnosis

Detection of specific antigens present in the sample (blood, urine, or CSF) using specific antibodies is the mainstay for the rapid diagnosis of infections.

Monoclonal Antibodies (mAb): Harvesting, Types, Applications

Monoclonal Antibodies (mAb): Harvesting, Types, Applications

These are antibodies derived from a single clone of a plasma cell. Monoclonal antibodies are used in the treatment of various diseases and cancers.

Heterophile Antigen: Examples, Diagnostic Applications

Heterophile Antigen: Examples, Diagnostic Applications

Heterophile antigens are antigens of similar nature found in phylogenetically unrelated species. They are involved in disease pathogenesis.

Coombs Test: Types, Principle, Procedure, Results

Coombs Test: Types, Principle, Procedure, Results

It is used to detect the presence of ‘incomplete’ Rh antibodies i.e. IgG antibodies capable of sensitising RBCs but incapable of causing hemagglutination.

Function of Antibodies (Immunoglobulins)

Function of Antibodies (Immunoglobulins)

Neutralization of pathogens, phagocytosis, mucosal immunity, ADCC and complement mediated lysis are major functions of antibodies.

Difference between B Cells and T Cells

Difference between B Cells and T Cells

B cells are major cells of humoral immunity, effector B cells produce antibodies. Find what Killer T-cells' and 'helper T-cells' do?

Superantigen (SAg): Examples and Roles

Superantigen (SAg): Examples and Roles

Superantigens are microbial peptides that can polyclonally activate up to 20% of T cells. e.g., Staphylococcal toxic shock toxin (TSST-1).

Antibodies in Disease Diagnosis

Antibodies in Disease Diagnosis

Detection of IgM, or Ab titre more than local cut-off titre or four-fold rise in Ab titre between acute and convalescent period is diagnostic.

T Dependent Antigen, T Independent Antigen

T Dependent Antigen, T Independent Antigen

B-cell response to T-dependent Ag requires assistance from helper T-cells but T-independent Ag can activate B cells without that help.

Immunoglobulin G (IgG): Structure, Subclasses, Functions

Immunoglobulin G (IgG): Structure, Subclasses, Functions

IgG antibody crosses the placenta and plays an important role in protecting the developing fetus. IgG is the most abundant Ig in serum.

Innate Immunity vs. Acquired Immunity

Innate Immunity vs. Acquired Immunity

Innate Immunity is present right from the birth but acquired or adaptive immunity is acquired during the course of life.

Primary vs. Secondary Immune Response

Primary vs. Secondary Immune Response

Primary immune response to Ag occurs on the first occasion. Subsequent encounter of B and T cells with same Ag leads to secondary response.

MHC Class I vs. MHC Class II Protein

MHC Class I vs. MHC Class II Protein

MHC molecules bind peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T cells.

Antigen and Factors Affecting Immunogenicity

Antigen and Factors Affecting Immunogenicity

Antigen is a foreign bio-molecule that induces a specific immune response and subsequently reacts with the products of the specific immune response.

Complement Pathways: Types, Functions, Regulation

Complement Pathways: Types, Functions, Regulation

Complement system is a part of the innate immune system

Western Blot Technique: Principle, Steps, Uses

Western Blot Technique: Principle, Steps, Uses

Western blotting or immunoblotting enables researchers to identify the specific protein from a mixture of proteins.

Immunization Schedule from Birth-18 Years (Infographics)

Immunization Schedule from Birth-18 Years (Infographics)

Vaccinations begin early, but regular doses continue through the first several years of childhood, with periodic updates and the addition of a few new vaccinations later on.

Immunoglobulin M (IgM): Structure, Properties, Functions

Immunoglobulin M (IgM): Structure, Properties, Functions

IgM is the largest pentameric immunoglobulin which is used as a marker of recent infection. IgM also activates complement pathway.

Widal Test: Principle, Procedure, Results, Limitation

Widal Test: Principle, Procedure, Results, Limitation

Widal test is one of the oldest and most widely used serological tests for the diagnosis of enteric fever.

Complement Fixation Test: Principle, Procedure, Results

Complement Fixation Test: Principle, Procedure, Results

In the presence of specific Abs to an infectious agent, any complement in the system is bound, leaving no residual complement for rxn with Abs to the RBCs.

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Ways to Boost your immunity level

Counterimmunoelectrophoresis (CIE): Principle, Procedure, Uses

Counterimmunoelectrophoresis (CIE): Principle, Procedure, Uses

Counterimmunoelectrophoresis is a modification of Ouchterlony method that speeds up migration of an antigen and antibody by applying an electrical current.

Agglutination Tests: Types, Principle, Uses

Agglutination Tests: Types, Principle, Uses

Agglutination tests detect Ab or Ag and involve agglutination of particulate antigens (bacteria, RBCs or Ag- or Ag-coated latex particles).

Direct ELISA (Sandwich ELISA) Test for Antigen Detection

Direct ELISA (Sandwich ELISA) Test for Antigen Detection

ELISA Test: Principle, Types, and Uses

ELISA Test: Principle, Types, and Uses

Cell Mediated Immunity

Cell Mediated Immunity

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Cytokines: Types and Functions

Antigen-Antibody reactions: Agglutination and types

Antigen-Antibody reactions: Agglutination and types