classimmunodeficiency

Definition1048708 Immunodeficiency disorders are a group ofdisorders in which part of the immunesystem is missing or defective1048708 Therefore the bodys ability to fightinfections is impaired and the person isprone to frequent infections that aregenerally more severe last longer and healslowly1048708 In addition there may be increasedsusceptibility to some cancers

bull 2 general typesndash Primary

bull Result from some genetic or developmental defect

bull Develop in infants and young children

ndash Acquiredbull Develop as a direct consequence of some other recognized

cause

bull Develop in later life

Immunodeficiency Diseases


bull An inborn or primary immunodeficiency ndash Results from hereditary or congenital defects

that prevent proper functioning of innate humoral andor cell-mediated defenses

bull An acquired or secondary immunodeficiency ndash Results from exposure to various chemical

and biological agents

Primary Immunodeficiency Diseases

Table 185

SCIDs

bull Severe combined immunodeficiency

bull Bodyrsquos ability to make lymphocytes is impaired or nonexistent

bull High vulnerability to infection

bull Has been successfully treated using gene therapy

bull Result from a number of causesndash Sever stress

bull Suppression of cell-mediated immunity results from an excess production of corticosteroids which is toxic to T cells

ndash Malnutrition and environmental factorsbull Inhibits production of B cells and T cells

Acquired Immunodeficiency Diseases

bull Acquired immunodeficiency syndrome (AIDS)ndash Discovered in 1981 in the United States but is

now a worldwide pandemic

ndash Defined as the presence of opportunistic or rare infections associated with the presence of human immunodeficiency virus (HIV)


Opportunistic Infections Associated with AIDS

Table 186

bull Human immunodeficiency virus (HIV)ndash Likely arose from mutation of the simian

immunodeficiency virus (SIV) found in African chimpanzees

ndash Enveloped positive single-stranded RNA virus

ndash Categorized as a retrovirus (Family Retroviridae) because it uses reverse transcriptase to make DNA copy of its genome

ndash Two major typesbull HIV-1 is prevalent in the United States and Europe

bull HIV-2 is prevalent in West Africa

Acquired Immunodeficiency Syndrome

HIV Attachment Entry into Host Cell

Figure 1816

Action of Reverse Transcriptase

Figure 1817

HIV Replication Cycle

Figure 1818

bull Because AIDS arises from the loss of helper T cellsndash Both humoral and cell-mediated immune

responses are impaired

T Cell Decline

bull Release of new viral particles kills the host T cell

bull The body is constantly making new T cells but cannot outpace the rate of destruction

bull As infection proceeds T cell numbers inevitably decline

bull Diagnosisndash Serological diagnosis involves detecting antibodies

against HIVbull A positive test indicates infection with HIV but not the

presence of AIDS

ndash Signs and symptoms of AIDS vary according to the diseases present

ndash Long term nonprogressors appear not to develop AIDS

bull May be due to defective virions or lack of effective coreceptors for the virus


bull Treatmentndash Highly active retroviral therapy (HAART)

bull A ldquococktailrdquo of several antiviral drugs

bull Reduces viral replication but the infection remains

ndash The various diseases associated with AIDS are treated on an individual basis

ndash Vaccine development is difficult because various problems must be overcome


Effect of T Cell Decline

bull CD4 helper T cells play a vital role in immune function

bull They are required for both cell-mediated and antibody-mediated immunity

bull Infected individual becomes vulnerable to other infections which eventually result in death

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SCIDs

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T Cell Decline

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bull 2 general typesndash Primary

bull Result from some genetic or developmental defect

bull Develop in infants and young children

ndash Acquiredbull Develop as a direct consequence of some other recognized

cause

bull Develop in later life








Table 185

SCIDs














Table 186









Figure 1816


Figure 1817


Figure 1818



T Cell Decline






presence of AIDS















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SCIDs

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T Cell Decline

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Table 185

SCIDs














Table 186









Figure 1816


Figure 1817


Figure 1818



T Cell Decline






presence of AIDS















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SCIDs

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T Cell Decline

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SCIDs














Table 186









Figure 1816


Figure 1817


Figure 1818



T Cell Decline






presence of AIDS















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SCIDs

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T Cell Decline

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Table 186









Figure 1816


Figure 1817


Figure 1818



T Cell Decline






presence of AIDS















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SCIDs

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T Cell Decline

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Figure 1816


Figure 1817


Figure 1818



T Cell Decline






presence of AIDS















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SCIDs

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T Cell Decline

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Figure 1817


Figure 1818



T Cell Decline






presence of AIDS















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SCIDs

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T Cell Decline

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Figure 1818



T Cell Decline






presence of AIDS















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SCIDs

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T Cell Decline

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T Cell Decline






presence of AIDS















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SCIDs

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T Cell Decline

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presence of AIDS















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SCIDs

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T Cell Decline

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T Cell Decline

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classimmunodeficiency

Technology

host t cell

t cell numbers

new t cells

loss of helper t cells

andor cellmediated defenses

immunodeficiency diseases

frequent infections

immune function