Ultimately HIV causes AIDS by depleting the CD
T-helper lymphocytes. This weakens the immune
system and allows opportunist infections. T-lymphocytes are essential to the
immune response and without them, the body cannot fight infections or kill
cancerous cells (Helz et al., 2006).
T-helper lymphocytes. This weakens the immunesystem and allows opportunist infections. T-lymphocytes are essential to the
immune response and without them, the body cannot fight infections or kill
cancerous cells (Helz et al., 2006).
During the acute phase of HIV infection, HIV induced
cell lysis and killing of infected cells by cytotoxic T cells account for CD4+
T-cell depletion, although apoptosis may also be a factor. During the chronic
phase, the consequences of generalized immune activation coupled with the gradual
loss of the ability of immune system to generate new T-cell depletion appear to account for the slow decline in CD4+
T-cells numbers although, the symptoms of immune deficiency characteristics of
AIDS do not appear for years after a person is infected, the bulk of CD4+
T-cell lost occur during the first weeks of infections, especially in the
intestinal mucosa, which harbours the majority of the lymphocytes found in the
body. The reason for the preferential loss of mucosal CD4+ T-cell is that a
majority of mucosal CD4+ express the CCR5+T- cells in the blood stream do so.
cell lysis and killing of infected cells by cytotoxic T cells account for CD4+
T-cell depletion, although apoptosis may also be a factor. During the chronic
phase, the consequences of generalized immune activation coupled with the gradual
loss of the ability of immune system to generate new T-cell depletion appear to account for the slow decline in CD4+
T-cells numbers although, the symptoms of immune deficiency characteristics of
AIDS do not appear for years after a person is infected, the bulk of CD4+
T-cell lost occur during the first weeks of infections, especially in the
intestinal mucosa, which harbours the majority of the lymphocytes found in the
body. The reason for the preferential loss of mucosal CD4+ T-cell is that a
majority of mucosal CD4+ express the CCR5+T- cells in the blood stream do so.
HIV seeks out and destroys CCR5 expressing CD4+
T-cell during acute infection. However, CD4+T-cells in mucosal tissues remain
depleted throughout the infection, although enough remain to initially ward off
life threatening infections (Apppay and Sauce, 2008).
T-cell during acute infection. However, CD4+T-cells in mucosal tissues remain
depleted throughout the infection, although enough remain to initially ward off
life threatening infections (Apppay and Sauce, 2008).
A major cause of CD4+T-cell loss appears to result
from their heightened susceptibility to apoptosis when the immune system
remains activated. Although new T-cells are continuously produced by the thymus
to replace the ones lost, the generative capacity of the thymus is slowly
destroyed by direct infection of its thymocytes by HIV. Eventually, the minimum
number of CD4+T-cells necessary to maintain a sufficient immune is lost leading
to AIDS.
from their heightened susceptibility to apoptosis when the immune system
remains activated. Although new T-cells are continuously produced by the thymus
to replace the ones lost, the generative capacity of the thymus is slowly
destroyed by direct infection of its thymocytes by HIV. Eventually, the minimum
number of CD4+T-cells necessary to maintain a sufficient immune is lost leading
to AIDS.
References
Appay; V, Sauce. D (2008): Immune Activation and Inflammation
in HIV-1 infection: Cause and Consequences. J.
Pathol. 214(2): 231-241.
in HIV-1 infection: Cause and Consequences. J.
Pathol. 214(2): 231-241.
Helz, M. and Mestecky. J. (2006): HIV Infection First
Battle Decides War”: Trend Immunol. 27(6):
274-281.
Battle Decides War”: Trend Immunol. 27(6):
274-281.
