final program.qxd - Parallels Plesk Panel

OP 5.3
Immunology - Summary of advances in HIV during the last year
Guido Poli, San Raffaele Scientific Institute, Milano, Italy.
The immunology of HIV infection is typically characterized by "waves" of fashionable
models tending to the holistic explanation of the reasons for failing viral clearance and,
conversely, indicating which directions should be taken for solving this modern plague.
In terms of the immune response, most of the emphasis in recent years has been
attributed to the cellular (CD4 and CD8) rather than humoral (antibody, Ab) immune
response to the virus; several experimental vaccine trials have been designed and are
under current evaluation in light of the hypothesis that, indeed, a robust, multi-targeting
cellular immune response to the virus would provide the key, if not to viral eradication, to
prolonged, therapy-free control of viral replication and pathogenesis. Unfortunately, most
of the studies, while providing interesting insights in terms of the defects characterizing
both CD4+ T helper cells and cytolytic T cells (CTL) in HIV infection (such as the
unbalanced expression of interferon-γ and interleukin-2, this latter being substantially
defective, in CTL of HIV+ individuals) have not indicated thus far a clear direction to
undertake. Conversely, a "renaissance" period of great interest in the capacity of Ab to
prevent and control early infection has been substantiated by both animal studies and by
experimental clinical trials in humans showing (partial) protective effects against SIV/HIV
infection by combinations of anti-Env monoclonal Abs. In this regard, the potential role of
autoreactive Ab displaying neutralizing activities against the virus has been recently
debated. In terms of pathogenesis, infection of the gut-associated (mucosal) lymphoid
tissue (GALT) has replaced the previous emphasis on other secondary lymphoid tissue
such as lymph nodes, although the implication of these studies may have been
overemphasized. The modalities of resistance and susceptibility to infection via genital
mucosa, a dominant modality of HIV transmission in both the developed and
underdeveloped countries, including the hypothesis that resting CD4+ T cells are the
primary sites of an initial productive infection, remain to be validated and fully understood
in the perspective of developing safe and effective microbicides as part of a preventive
strategy against the infection.
“ Focusing FIRST on PEOPLE “ 50 w w w . i s h e i d . c o m