(HealthDay News) – For two HIV-1 infected patients who underwent reduced-intensity conditioning allogeneic hematopoietic stem cell transplantation (RIC alloHSCT), HIV-1 remained undetectable in peripheral blood and rectal tissue up to 4.3 years after transplantation, according to a study presented at the International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention, held from June 30–July 3 in Kuala Lumpur, Malaysia.

Timothy J. Henrich, MD, from Brigham and Women’s Hospital in Boston, and colleagues examined the longitudinal effects of HSCT on host microchimerism and HIV-specific cellular immunity. Peripheral blood mononuclear cells (PBMCs), obtained by leukapheresis, were tested for residual HIV-1 DNA or replication-competent proviruses up to 4.3 years following RIC alloHSCT. Participants included two HIV patients who underwent RIC-alloHSCT, a third who died six months post-transplantation from recurrent lymphoma, and a fourth autologous HSCT patient who served as a control.

The researchers found that, in the two RIC-alloHSCT patients, no HIV-1 DNA was detected from PBMCs. In addition, no HIV-1 p24 antigen was detected by viral co-culture from purified CD4+ T cells, nor was any HIV-1 detected in rectal tissue. Post-HSCT, residual host cells constituted <0.001% of PBMCs. Before or after allogeneic or autologous HSCT, no human leukocyte antigen-specific or pooled HIV-1 peptides elicited a strong HIV-specific immune response.

“While stem cell transplantation is not a viable option for people with HIV on a broad scale because of its costs and complexity, these new cases could lead us to new approaches to treating, and ultimately even eradicating HIV,” Kevin Robert Frost, amfAR’s chief executive officer, said in a statement.

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