Biology Reference
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enhance our capabilities to analyze HIV-1 disease. The identi®cation of cells
that express viral proteins, the determination of the set of viral proteins ex-
pressed at a given time, and the analysis of variant viral strains are important
and signi®cant goals for investigators to achieve.
It is probably correct to assume that ¯ow cytometric analysis of HIV-1 pro-
teins by ¯ow cytometry has not been successful because the available antibodies
are not su½cient to detect viral proteins given the current sensitivity of the
technology. EAS may be helpful because it o¨ers a signi®cant enhancement in
the resolving power of ¯ow cytometry. Moreover, EAS may also be used to ®nd
new antibodies that would be informative but that have been discarded because
they did not work with the standard procedures for analyzing the cells.
We have used human anti-HIV-1 gp120 monoclonal antibodies to stain the
``latently'' infected cell line ACH-2. The cells were processed either by a stan-
dard ampli®cation procedure or by EAS ( Fig. 17.4). The results demonstrate
that EAS allows for the detection of heterogeneous levels of gp120 on the sur-
face of most ACH-2 cells. The uninfected parental cell line showed no speci®c
staining. The standard staining procedure did not detect most of the gp120-
expressing cells. It should be noted that another control was included: an anti-
Ebola virus antibody gave histograms identical to the control IgG1 (data not
shown). Also, similar results were obtained with another ``latently'' infected cell
line, J1.1, and its parent, Jurkat (data not shown). Finally, using EAS we also
Figure 17.4. ACH-2, ``latently'' infected with HIV-1, and CEM, the uninfected parental line to
ACH-2, were stained with two di¨erent anti-gp120 human monoclonal antibodies that had been
biotinylated (open histograms) or with control biotinylated IgG1 ( ®lled histograms). The cells were
processed for ¯ow cytometric analysis by standard ampli®cation (indirect staining; left panels) or by
EAS (middle and right panels).
