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HIV infection 331 HLA
Nuclear magnetic resonance (NMR) image of human immunologic deficiency
virus 1 (HIV-1) protease.
Human immunodeficiency virus 1 (HIV-1) reverse transcriptase.
Certain cytokines can influence the dynamics of HIV-1
infection by altering chemokine receptor expression levels
on hematopoietic cells. During chronic HIV-1 infection,
proinflammatory cytokines such as tumor necrosis factor
α (TNF-α) and interferon γ (IFN-γ) are secreted in excess.
IFN-γ increases cell surface expression of CCR-5 by human
mononuclear phagocytes and of CXCR-4 by primary
hematopoietic cells. In addition, GN-CSF can decrease and
interleukin-10 (IL10) can increase expression of CCR-5.
Further research into cytokine-mediated regulation of
chemokine receptors may lead to increased understanding
of how these receptors affect the pathogenesis of AIDS.
HIV infection
Recognition of infection by the human immunodeficiency
virus (HIV) is through seroconversion. Following conversion
to positive reactivity in an antibody screening test, a western
blot analysis is performed to confirm the result of positive
testing for HIV. HIV mainly affects the immune system and
the brain. It affects the CD4 + lymphocytes that are necessary
to initiate an immune response by interaction with antigenpresenting
cells, and thus deprives other cells of the immune
system from receiving a supply of interleukin-2 (IL2) through
CD4 + lymphocyte stimulation, leading to a progressive decline
in immune system function. HIV transmission is by sexual
contact, through blood products, or occurs horizontally from
mother to young. Although first observed in male homosexuals,
it later became a major problem of intravenous drug abusers
and ultimately has become more serious in the heterosexual
population, affecting increasing numbers of women and men.
Clinically, individuals may develop acute HIV mononucleosis
that usually occurs 2 to 6 weeks following infection, although it
may occur later. The main symptoms include headache, fever,
malaise, sore throat, and rash. Patients may develop pharyngitis;
generalized lymphadenopathy; a macular or urticarial rash
on the face, trunk, and limbs; and hepatosplenomegaly. The
severity of the symptoms may vary. Acute HIV infection may
also induce neurologic diseases including meningitis, encephalitis,
and other manifestations. Some individuals may not
develop symptoms or illness for years. Others develop AIDSrelated
complex (ARC), which represents progressive immune
dysfunction. Symptoms include fever, night sweats, weight
loss, chronic diarrhea, generalized lymphadenopathy, herpes
zoster, and oral lesions. Individuals with ARC may progress
to AIDS or death may occur in the ARC stage. ARC patients
do not revert to an asymptomatic condition. Other individuals
may develop persistent generalized lymphadenopathy (PGL)
characterized by enlarged lymph nodes in the neck, axilla, and
groin. The Centers for Disease Control (CDC) set up criteria
for the diagnosis of AIDS that include the individuals who
develop certain opportunistic infections and neoplasms, HIVrelated
encephalopathy, and HIV-induced wasting syndrome.
The most frequent opportunistic infections in AIDS patients
include Pneumocystis carinii, which produces pneumonia, and
Mycobacterium avium-intracellulare, among other microorganisms.
The most frequent tumor found in AIDS patients is
Kaposi’s sarcoma. At present, AIDS is 100% fatal.
HIV serology..
hives
A wheal-and-flare reaction of the anaphylactic type produced
in the skin as a consequence of histamine produced by
activated mast cells. The reaction is accompanied by edema,
erythema, and pruritus. Hives is a synonym for urticaria.
HL
Abbreviation for Hodgkin lymphoma.
HLA
Acronym for human leukocyte antigen. The HLA histocompatibility
system in humans represents a complex of
major histocompatibility complex (MHC) class I molecules
H