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Immunology Questions and Answers (Q&A)

There are so many ways to differentiate B cells from T cells. Below are some notable differences: B cells are produced in the bone marrow, and they also mature in the Bone marrow. These cells produce and secrete antibodies. Antibodies fight against pathogens that have gotten into the body. There are two types of B cells: the memory cells and plasma cells.

B cells have a B cell receptor, also known as BCR. T cells are also produced in the bone marrow, but they travel to the thymus where they mature. T cells identify viruses and microorganisms by the antigen-presenting cells (APC) present on the surface of the cell. There are two types of T cells: cytotoxic T cells and helper T cells. T cells have T cell receptor commonly referred to as TCR. Compared to B cells, T cells have a longer life span. I hope you find this information helpful.

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The correct answer is option D – Salmonella typhi Vi agglutination is seen in Salmonella typhi. Salmonella typhi is a gram-negative bacterium that can infect the gastrointestinal tract and the blood causing a disease commonly known as typhoid fever. Symptoms of infection often include high fever, fatigue, and headache, loss of appetite, constipation, or diarrhea.

Infection is mostly gotten through consumption of contaminated food and water. Vi antigen co agglutination is used to detect the presence of Salmonella typhi Vi antigen in the blood. This test shows a high level of sensitivity and specificity when compared with blood culture or widal titer test. It can be done to confirm the diagnosis of Salmonella typhi. This infection is treated with the use of antibiotics. I hope you find this information helpful.

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The correct answer is option C – Sheep erythrocytes. The most specific cells containing antigens that agglutinate with heterophile antibodies are sheep erythrocytes. Heterophile antibodies are weak antibodies than are produced due to responses to poorly defined antigens. The most common application is seen in mononuclear spot test, which is a form of heterophile antibody test in Epstein – Barr virus infection. Heterophile antibodies are significantly important in clinically detecting Epstein - Barr virus (EBV), which is the causative agent for infectious mononucleosis.

This test relies greatly on the agglutination of sheep Red blood cells (erythrocytes) with heterophile antibodies present in the patient’s serum. Although human erythrocytes and horse erythrocytes have antigen that can agglutinate with heterophile antibodies, sheep erythrocyte is the most specific cell containing antigen that can agglutinate with heterophile antibodies.

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Correct answer is option E
Class III MHC genes have immune related functions. These genes encode for some complement proteins, cytokines and heat shock proteins. The MHC class III genes have the highest gene density but some of the genes are not involve in the immune systems.

Class I MHC molecules are found on all nucleated cells in the body and the bind to CD 8+ T cells. The MHC I gene encodes for CD 8+ T cells.

Class II MHC molecules are found on antigen presenting cells, macrophages, dendritic cells and B cells. These cells bind to CD 4+ T cells. The MHC II gene encodes for CD4+ T cells.

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Macrophages are the type of Antigen Presenting Cells (APC) that are critical in the uptake and presentation of antigen to T cells. APC are specialized cells that show the antigen complex on their surfaces with major histocompatibility complexes (MHCs).

Macrophages, B cells and dendritic cells are termed “professional APC” as they present antigen to helper T cells. Macrophages are stimulated by interferon-gamma, which is secreted by T cell. This, in turn, causes the expression of MHC class II on the surface of macrophages and the secretion of many costimulatory molecules. Macrophages can engulf and phagocytose fragments of antigen and present them to helper T cells.

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The correct answer to this question is option B – CSF can be used as a specimen for VDRL. VDRL is an acronym for Venereal Disease Research Laboratory, and RPR is the acronym for Rapid Plasma Reagin. One major advantage that VDRL has over RPR is that VDRL can use Cerebrospinal Fluid (CSF) as a specimen for the test. This gives VDRL an edge over RPR when it comes to the use of CSF as a specimen. RPR is much advanced and developed than VDRL.

It is the most preferred test for syphilis because it can be easily done. For the VDRL test, the specimen most be heated before the test can be done, but this is not the case for RPR. RPR is more effective in detecting syphilis infection. RPR can also be done with the use of a microscope, as a result, is visible with the naked eye. The reverse is the case for VDRL.

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The C5 convertase in classical pathway of complement is C4b2a3b notC4b2b3b

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Release of histamine and other mediators is supposed to be the correct answer.

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The polypeptide chain is formed from amino acids that are linked together by peptide bonds. Many amino acids come together to form a polypeptide chain. The amino acid is the building block of the polypeptide chain as polypeptide chains form the building block of proteins. Polypeptides are formed during the process of translation in the cell cycle. This is the process of building the polypeptide chain. Based on the codons present of mRNA (Messenger Ribonucleic Acid), amino acids are added to the growing chain. Amino acids are carried by different tRNA (Transfer Ribonucleic Acids), which are specific to each amino acid.

Many enzymes, channels, and structures needed for the normal functioning of our body are made from polypeptide chains. Di peptide refers to a chain with two amino acids. Tri peptide chain has three amino acids. The tetrapeptide chain has four amino acids, and oligopeptide means less than 10. The term Poly peptide refers to a chain that has more than ten amino acids. I hope you find this information helpful.

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