AEGiS-CATIE: TreatmentUpdate: Ritonavir -- what really happens to the immune system

TreatmentUpdate: Ritonavir -- what really happens to the immune system

TreatmentUpdate 76. 9(2): 5; March, 1997
Sean Hosein

This article is based on information presented at the 4th Conference on Retroviruses and Opportunistic Infections in Washington, DC, January 22-26, 1997.

Background

A research team in France studied the effect of combination anti-HIV therapy on levels of different types of CD4+ cells in the blood. Doctors gave the subjects ritonavir alone for the first 15 days and then added AZT and ddC. Although the researchers enrolled 20 subjects, they only reported data on 8. At the start of the study, 4 of the 8 subjects had 166 cells.

On average, the CD4+ cell count increased by 190 cells and the amount of HIV in the blood fell to 1/1,000th its pre-study level.

What kind of cells?

The increased numbers of CD4+ cells that appeared in the blood during the first 3 months of therapy were not new. These cells had simply been moved from lymph nodes/tissues and sent into the blood. After 3 months of therapy, researchers detected CD4+ cells that they called ?na ve?. Na ve T cells are not activated ? only in an activated state can T cells attack HIV or other germs. So the usefulness of these na ve T cells is not yet clear.

A year after the study started, technicians detected a decrease the type of cell described as Type 0/Type 2 in a few subjects. These cells cannot produce the chemical response needed to fight many of the infections seen in AIDS, so perhaps this decrease may be a good sign. Researchers will have a clearer picture as results come in from more sophisticated studies carried out over several years.

REFERENCES:

1.Autran B, Mathez D, Carcelain G, et al. Dynamics of the CD4+ T helper cell subset reconstitution after combined anti-retroviral therapies. Oral presentation, abstract 34.

2. Connors M, Kovacs JA, Gea-Banacloche JC, et al. HIV induces changes in CD4+ T cell phenotype and repertoire that are not immediately restored by antiviral or immune-based therapies. Oral presentation, abstract 369.

3. Bachmann MF, Kundig TM, Hengartner H and Zinkernagel RM. Protection against immunopathological consequences of a viral infection by activated but not resting cytotoxic T cells: T cell memory without ?memory T cells.?? Proceedings of the National Academy of Sciences USA 1997;94:640-645.

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Copyright © 1997 - TreatmentUpdate. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Editor, The Canadian AIDS Treatment Information Exchange, 555 Richmond St. West, Suite 505, Box 1104, Toronto, ON, M5V 3B1 • Phone: 416-203-7122 • Toll Free: 1-800-263-1638 • Fax: 416-203-8284 http://www.catie.ca

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