All questions of Immune System (BIO) for MCAT Exam

The Widal test is one method that may be used to help make a presumptive diagnosis of enteric fever, also known as typhoid fever.The test was based on demonstrating the presence of agglutinin (antibody) in the serum of an infected patient, against the H (flagellar) and O (somatic) antigens ofSalmonella typhi.

Its given in 12th NCERT.... widal test for typhoid

When a mosquito feeds on an infected person, the mosquito can become infected and can bite and infect others. The Aedes aegypti and Aedes albopictus mosquitoes transmit chikungunya. They also transmit dengue fever, another disease caused by a virus.

Antibodies are produced by specialized white blood cells called B lymphocytes (or B cells). When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone.

Human immunodeficiency virus infection and acquired immune deficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV).Following initial infection, a person may not notice any symptoms or may experience a brief period of influenza-like illness. Typically, this is followed by a prolonged period with no symptoms. As the infection progresses, it interferes more with the immune system, increasing the risk of developing common infections such as tuberculosis, as well as other opportunistic infections, and tumors that rarely affect people who have working immune systems.[5] These late symptoms of infection are referred to as acquired immunodeficiency syndrome (AIDS).This stage is often also associated with unintended weight loss.

Sporozoite is the infective stage of the malarial parasite. They are present in the saliva of infected female anopheles mosquito.

Anti venom against snake poison contains antibodies.

Explanation:
Anti venom is a serum that is used to treat snake bites. It contains antibodies that are specifically produced to neutralize the venom of a particular snake species. The antibodies are produced by injecting a small amount of the snake venom into an animal, usually a horse, and then collecting the blood serum from the animal after a certain period of time. This serum contains the antibodies that have been produced in response to the venom.

The antibodies in the anti venom work by binding to the venom molecules and neutralizing their toxic effects. This prevents the venom from causing damage to the body and allows the body's own immune system to clear the venom from the bloodstream.

It is important to note that anti venom is specific to the species of snake that produced the venom. This means that anti venom for one species of snake will not be effective against the venom of another species. It is also important to administer anti venom as soon as possible after a snake bite, as the venom can rapidly spread through the body and cause severe damage if left untreated.

The function of IgE antibody as mediators in allergic reactions of Type I is explained by their ability to interact both with antigen and with receptor molecules on the membrane of blood basophils and tissue mast cells. However, it is not understood how the interaction of an allergen with cell-bound IgE antibody will induce basophil (mast) cells to release a great number of biologically active substances of which some will be further discussed at this meeting, nor is it known what role the IgE-mast cell system plays in the development and control of a normal immune response.

Transmission of Japanese Encephalitis

Japanese Encephalitis is a viral disease that is transmitted by mosquitoes. The Japanese encephalitis virus (JEV) is a flavivirus that is transmitted to humans through the bite of infected mosquitoes. The virus is primarily found in rural and agricultural areas of Asia, but cases have been reported in other parts of the world as well.

Mosquitoes that transmit Japanese encephalitis

The Culex mosquitoes are the primary vector for the transmission of Japanese encephalitis. These mosquitoes are common in rural areas and are most active during the evening and early morning hours. The mosquito becomes infected with the virus when it feeds on an infected animal, usually a pig or a bird. The virus then multiplies in the mosquito's salivary glands and can be transmitted to humans when the mosquito bites a person.

Risk factors for Japanese encephalitis

People who live or travel to areas where Japanese encephalitis is endemic are at risk of contracting the disease. The risk is greatest during the monsoon season when mosquitoes are most active. Children and older adults are at greater risk of developing severe disease if they become infected with the virus.

Prevention of Japanese encephalitis

The best way to prevent Japanese encephalitis is to get vaccinated before traveling to areas where the disease is endemic. Other preventive measures include:

- Wear long-sleeved shirts and pants when outdoors
- Use insect repellent containing DEET on exposed skin
- Use mosquito nets or screens in sleeping areas
- Eliminate standing water around homes where mosquitoes breed

Conclusion

Japanese encephalitis is a serious disease that is transmitted by mosquitoes. The primary vector for the transmission of the virus is the Culex mosquito. People who live or travel to areas where Japanese encephalitis is endemic should take preventive measures to reduce their risk of contracting the disease. Vaccination is the most effective way to prevent Japanese encephalitis.

"HIV " Attacks CD4 cells (T- helper, T- cells) .. this cells plays important role in immune system..

's own antigens during development

b)Detection of foreign antigens by T cells

c)Recognition of self antigens by natural killer cells

d)Binding of antibodies to self antigens

Understanding Myelogenous Leukemias
Myelogenous leukemias are a type of cancer that arises from the uncontrolled proliferation of myeloid cells, which are part of the innate immune system. To understand why the bone marrow is the most likely site for this production, let’s delve into the roles of different tissues involved in hematopoiesis.
Bone Marrow: The Primary Site of Hematopoiesis
- The bone marrow is the primary site where all blood cells, including myeloid and lymphoid lineages, are produced.
- Myelogenous leukemias specifically involve myeloid cells, which include granulocytes, monocytes, erythrocytes, and platelets, all generated from hematopoietic stem cells in the bone marrow.
- In cases of myelogenous leukemia, mutations occur in the DNA of these progenitor cells, leading to the uncontrolled growth of myeloid lineage cells.
Other Tissues: Thymus, Spleen, and Lymph Nodes
- The thymus primarily functions in the maturation of T lymphocytes, not myeloid cells, making it irrelevant for myelogenous leukemias.
- The spleen and lymph nodes are involved in filtering blood and lymph, respectively, and play roles in the adaptive immune response, but they are not the sites of initial blood cell production.
- While these organs can be affected by leukemic cells as the disease progresses, they do not produce myelogenous leukemias.
Conclusion
In summary, the bone marrow is indeed the correct answer as it is the primary site where myeloid cells are produced and where the malignant transformation leading to myelogenous leukemias occurs.

Overview of Innate Immune Cell Types
The innate immune system is the body's first line of defense against pathogens. It includes various cell types that perform different functions, notably phagocytosis, which is the process of engulfing and digesting harmful entities like bacteria and dead cells.
Cell Types Discussed
- Neutrophils:
- These are the most abundant white blood cells in the immune system.
- They are highly effective at phagocytosing bacteria and fungi, serving as the first responders to sites of infection.
- Macrophages:
- Derived from monocytes, macrophages are large phagocytic cells.
- They play a crucial role in engulfing pathogens, dead cells, and debris, and also help activate other immune cells.
- Eosinophils:
- These cells are primarily involved in combating multicellular parasites and certain infections.
- They can also perform phagocytosis, although it's not their primary function.
- Basophils:
- Basophils are the least common type of granulocytes and do not perform phagocytosis.
- They primarily release histamines and other mediators during allergic reactions and inflammatory responses, aiding in vasodilation and increasing blood flow to affected tissues.
Conclusion
In summary, basophils (option B) are the correct answer as they do not engage in phagocytosis. Instead, they release substances that play a role in allergic reactions and inflammation, differentiating them from neutrophils, macrophages, and eosinophils, which are all capable of phagocytosis.