BT302 Final Term Notes

CHAPTER # 21

What is immunodeficiency?

The deficiency or failure of immune system is called as immunodeficiency. It is a state of complete absence of immunity or effective immune response. There are defects regarding generation of immune reactivity against infectious agents like bacteria & virus etc. There is no immune response against transformed cells like tumours or malignancy.

Who are immunodeficient patients?

The persons having immunodeficiency are also called as immunocompromised patients because there is increased vulnerability for opportunistic infections in addition to other forms of infections. As there is decrease surveillance against tumours so more chances of getting tumours are there in immunodeficient patients.

How many categories are classified of Immunodeficiency?

Immunodeficiency is classified into two main categories based on mode of acquiring

1. Primary Immunodeficiency
2. Secondary Immunodeficiency

Explain the Classification of Immunodeficiency?

Primary immunodeficiency is basically the inherited or congenital defects of the immune system. These defects can be either in specific or non-specific immune systems. Primary immunodeficiency diseases can occur in individuals of any age. These are classified based on the site of lesion in the developmental or differential pathway of immune system. The chances of susceptibility to variety of infections get increased in this kind of immunodeficiency. The nature of infection depends on the kind of immunodeficiency. There are more than 400 primary immunodeficiencies. Some are relatively common, while others are quite rare. Some affect a single cell or protein of the immune system and others may affect two or more components of the immune system. This kind of immunodeficiency is not congenital in nature in contract to primary immunodeficiency. This state of immunodeficiency is associated with infections for example AIDS. There is also association of aging factor like hypo-cellularity in bone marrow. Malignancies for example Leukaemia and Myeloma are also linked with secondary immunodeficiency. Furthermore, other metabolic disorder like diabetes and renal malfunction etc. are also linked with secondary immunodeficiency. The most common secondary immune deficiencies are caused by aging, malnutrition, certain medications and some infections, such as HIV.

Write down the kinds of Primary immunodeficiency?

Primary immunodeficiency can be of two kinds

Immunodeficiency in specific immune system

Those conditions due to defects of the adaptive immune system in which defence is carried out in a more specific manner by T-cells and antibody producing B-cells. This kind of immunodeficiency is due to defects in stem cell differentiation.

Immunodeficiency in Non-Specific immune system

Those fewer common conditions with defects in the innate immune system, a system of cells and mechanisms that defend the host from infection in a non-specific manner.

Write down the important disease of immunodeficiency in specific immune system in Primary Immunodeficiency?

Followings are the important disease of immunodeficiency in specific immune system

Reticular dysgenesis

It is either complete absence or severe deficiency of lymphocytes & granulocytes in blood due to decrease differentiation of bone marrow stem cells.

Severe combined immunodeficiency (SCID)

This disorder is due to the involvement of lymphoid stem cells. There is complete absence of T & B cell immunity. The patients suffering from SCID are susceptible to variety of bacterial, viral, mycotic & protozoan infections.

This is the disorder of T-lymphocytes due to congenital thymic aplasia or hypoplasia. This condition is highly immunodeficient as live vaccines also cause infections in the patients suffering from DiGeorge syndrome.

This kind of immunodeficiency is due to functional disorder of B-Lymphocytes. Such patients are highly susceptible to recurrent bacterial infections.

There is deficiency of IgA in this disorder as a result individuals are susceptible to mucosal surface infections like GIT, eye & nasopharynx.

Selective IgG deficiency

In this kind of immunodeficiency, there is selective deficiency of IgG which leads towards hyper IgM immunodeficiency.

Write down the important disease of immunodeficiency in Non-Specific immune system in Primary Immunodeficiency?

Followings are the important conditions which are linked with immunodeficiency in nonspecific immune system

Cyclic Neutropenia

There is low number of circulating neutrophils in the blood which cause recurrent bacterial infections among such patients.

This kind of immunodeficiency is due to defects in phagocyte functions.

Complement deficiency

There is deficiency of complement proteins in this kind of immunodeficiency. Patients suffering from such disorder are susceptible to infections particularly Neisseria.

What is AIDS?

Acquired Immunodeficiency Syndrome (AIDS). This condition is caused by a virus called as human immunodeficiency virus (HIV). This condition is initiated through an initial infection with influenza like illness. Further, the disease progress with other defects in immune system leading towards severe immunodeficiency. The patients get severe opportunistic infections like tuberculosis. Moreover, the chance of getting tumour also increased. AIDS is linked with abnormalities in circular lymphocytes. AIDS patients have also increased susceptibility to various following tumours

• Kaposi sarcoma
• Burkitt’s lymphoma
• Primary central nervous system lymphoma

Write down the mode of transmission of AIDS?

For AIDS, HIV infection is transmitted by following two modes