Biology Reference
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Figure 10.1. Detection of HIV-1-infected AM by ¯ow cytometry. AM of healthy donors were
infected with HIV-1 BAL isolate in vitro and cultured for 14 days, the cells detached, permeabilized
and stained with phycoerythrin (PE)-conjugated KC57 antibody (which recognizes HIV-1 p24 core
antigens). Compared with a PE-conjugated isotype control, live-gating on AM revealed 87% of the
AM were positive for the HIV-1 p24 antigen. For details see Ieong et al., 2000. Reproduced with
permission.
portant coreceptors for HIV infection of susceptible cells. However, HIV-1
preferentially utilizes the CCR5 chemokine receptor in AM (Park et al., 1999).
HIV-1 infected AM may represent previously HIV-1-infected peripheral
blood monocytes that are recruited into the lungs and di¨erentiate into HIV-1-
infected AM. Alternatively, uninfected AM may become HIV infected in the
alveolar airspace from the release of HIV-1 virions from actively replicating
T lymphocytes. Terminally di¨erentiated macrophages such as AM are more
susceptible to HIV-1 infection compared with peripheral blood monocytes
(Rich et al., 1992). Evidence suggests that HIV-1 evolves di¨erently in blood
than in lung macrophage populations (Nakata et al., 1995), suggesting that
lung-speci®c or local in¯uences can in¯uence the genetic development of HIV-1.
AM may be more frequently infected with HIV-1 in pediatric patients com-
pared with adult patients (Pearce et al., 1993).
HIV-1 Replication in Alveolar Macrophages
In general, HIV-1 infection of AM is latent, with predominantly proviral DNA
detectable. HIV-1 RNA, indicative of active viral replication, can be detected in
the cell-free BAL ¯uid in up to 16% of asymptomatic HIV-infected individuals,
but is detectable in the BAL ¯uid in 82% of HIV-infected persons with active
lung disease such as Pneumocystis carinii pneumonia (Koziel et al., 1999). Im-
portantly, the levels of HIV-1 RNA greatly exceed those measured in the serum
of the same patients, suggesting local HIV-1 replication in the lungs of these
individuals rather than exudation from the serum ( Koziel et al., 1999).
