An anti-CD45RO immunotoxin eliminates T cells latently infected with HIV-1in vitro

Despite the success of highly active antiretroviral therapy (HAART) in lowe ring circulating HIV-1 to undetectable levels in most infected individuals, several studies have documented the presence of a small reservoir of laten tly infected cells in HAART patients, the majority of which are CD45RO(+) m emory T cells. We previously have demonstrated that latently infected, repl ication-competent cells can be generated in vitro after eliminating CD25(+) cells with an immunotoxin (IT), The present study was designed to determin e whether these latent cells could be eliminated by an anti-CD45RO IT. Our results indicate that the anti-CD45RO IT eliminates >99%, of either M-tropi c or T-tropic virus produced by the latently infected cells after mitogen s timulation. This IT also appears to be as effective as the anti-CD25 IT in eliminating the activated, HIV-1-producing cells, In contrast, the anti-CD4 5RO IT does not kill CD45RA(+) naive cells. Further studies using cells fro m HIV-1-infected individuals on HAART will be necessary to determine the po tential clinical utility of this IT.