Widal Test- Objective, Principle, Procedure, Types, Results, Advantages and Limitations

Result Interpretation of Widal Test

Widal test is an agglutination test which detects the presence of antibodies in patient’s serum produced against the causative agents of enteric fever (Salmonella Typhi and Salmonella Paratyphi A, B and C). It is one of the common methods employed for serological diagnosis of typhoid and paratyphoid fever especially in the endemic regions. The test was … Read moreWidal Test- Objective, Principle, Procedure, Types, Results, Advantages and Limitations

Immunoglobulin E (IgE)- Structure and Functions

Immunoglobulin E (IgE)- Structure and Functions

Immunoglobulin E (IgE) is one of the 5 classes of immunoglobulins, which is defined by the presence of epsilon (ε) heavy chain. It is present in circulation at very low concentrations of less than 1 µg/mL which is approximately 300-fold lower than that of IgG. Although least abundant, it is in many respects the most … Read moreImmunoglobulin E (IgE)- Structure and Functions

Anatomical Barriers of Immune System- Skin and Mucus

Anatomical Barriers of Immune System- Skin and Mucus

Before a microbe or parasite can invade the host and cause infection, it must first attach to and penetrate the surface epithelial layers of the body. Organisms gain entrance into the body by active or passive means. For example, actively, they might burrow through the skin, while passively be ingested in food, inhaled into the … Read moreAnatomical Barriers of Immune System- Skin and Mucus

Immunoglobulin D (IgD)- Structure and Functions

Immunoglobulin D (IgD)- Structure and Functions

Immunoglobulin D (IgD) is a unique immunoglobulin with a low concentration in serum and the exact function of which is not known. IgD represents about 0.25% of the total serum immunoglobulins and has a relative molecular mass of 185 kDa while a half-life of 2.8 days, similar to that of IgE. However, it makes up about 1% … Read moreImmunoglobulin D (IgD)- Structure and Functions

Inflammation

Inflammation

lnflammation or inflammatory response is defined as the biological response of the immune system especially vascular tissues to harmful stimuli, such as microorganisms or other foreign substances. It occurs when tissues are injured by microbes, trauma, toxins, heat, or any other cause and hence is the body’s normal protective response against infection or injury. It … Read moreInflammation

Non-Specific Immune Response

Non-Specific Immune Response

Defence mechanism refers to the ways in which the body protects itself from invasion of pathogenic organisms or other foreign materials such that it provides defence against their harmful effects. The defence mechanism employed may be achieved through either specific or non-specific mechanisms. Non-specific defence mechanisms are termed so as it offers resistance or protection … Read moreNon-Specific Immune Response

Differences Between Antigenic Shift and Antigenic Drift

Differences Between Antigenic Shift and Antigenic Drift

Differences Between Antigenic Shift and Antigenic Drift Here are some differences: S.N. Characteristics Antigenic Shift Antigenic Drift 1. Definition Antigenic shift refers to the gene recombination occurring when influenza viruses re-assort. Mutations causing minute changes in the hemagglutinin and neuraminidase antigens on the surface of the Influenza virus is termed as antigenic drift. 2. Result in … Read moreDifferences Between Antigenic Shift and Antigenic Drift

Immunoglobulin M (IgM)- Structure and Functions

Immunoglobulin M (IgM)- Structure and Functions

Immunoglobulin M (IgM) is an antigen receptor on B cells and the first antibody produced in an immune response. It is present both on B cells, and as a soluble molecule in the blood. Because of its large size (900 kDa), IgM is found primarily in the intravascular space i.e. in the bloodstream and also … Read moreImmunoglobulin M (IgM)- Structure and Functions

Mucosa Associated Lymphoid Tissues (MALT)

Mucosa Associated Lymphoid Tissues (MALT)

The main sites of entry for microbes into the body are through mucosal surfaces. Hence, the majority (>50%) of lymphoid tissue in the human body is located within the lining of the respiratory, digestive and genitourinary tracts. Small concentrations of lymphoid tissue are also found in thyroid, breast, lung, salivary glands, eye, and skin. Image Source: DOI: 10.1183/13993003.01701-2015 These lymphoid tissues collectively are thus … Read moreMucosa Associated Lymphoid Tissues (MALT)

Immunoglobulin A (IgA)- Structure, Subclasses and Functions

Immunoglobulin A (IgA)- Structure, Subclasses and Functions

Antibodies, or ‘immunoglobulins’, are glycoproteins that bind antigens with high specificity and affinity. In humans there are five chemically and physically distinct classes of antibodies (IgG, IgA, IgM, IgD, IgE). Immunoglobulin A (IgA), is the major class of antibody present in the mucosal secretions of most mammals. It is the key first line of defence … Read moreImmunoglobulin A (IgA)- Structure, Subclasses and Functions