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

Despite the success of highly active antiretroviral therapy (HAART) in lowering circulating HIV-1 to undetectable levels in most infected individuals, several studies have documented the presence of a small reservoir of latently infected cells in HAART patients, the majority of which are CD45RO(+) memory T cells. We previously have demonstrated that latently infected, replication-competent cells can be generated in vitro after eliminating CD25(+) cells with an immunotoxin (IT). The present study was designed to determine 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-tropic or T-tropic virus produced by the latently infected cells after mitogen stimulation. 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-CD45RO IT does not kill CD45RA(+) naive cells. Further studies using cells from HIV-1-infected individuals on HAART will be necessary to determine the potential clinical utility of this IT.