How good are new CD4 cells on HAART?

Keith Alcorn
Estimated reading time 1 minutes
This article is more than 24 years old.

The CD4+ cell responses seen in people who experience immune restoration on HAART appear to be just as good, if not better, than those of untreated people of an equivalent CD4+ cell count who have not yet experienced any CD4+ cell decline, Dr Michael Lederman of Case Western Reserve University told the Fifth International Congress on Drug Therapy in HIV Infection this week.

Although impressive increases in CD4+ cell numbers have been seen in response to therapy, and virtually no relapse of prior opportunistic illnesses after immune restoration, doubts have persisted in some quarters over the quality of the CD4+ cell response to non-prevalent antigens. Proliferative responses to antigens and delayed hypersensitivity skin test reactions were poor in a high proportion of individuals experiencing the early stages of immune restoration. What difference does approximately two and half years of treatment, and a restoration of the CD4+ cell count to the lower end of normal, make to these responses?

Dr Lederman studied two age matched groups of patients, one untreated group with a mean CD4 cell count of 558 (n=20) and another group of PI-treated individuals with a mean CD4 cell count of 552 after 35 months prior HAART, and a nadir CD4 cell count of 213 prior to commencing HAART (n=15).

Glossary

p24

An HIV antigen that makes up most of the HIV viral core. High levels of p24 are present in the blood during the short period between HIV infection and seroconversion, before fading away. Since p24 antigen is usually detectable a few days before HIV antibodies, a diagnostic test that can detect p24 has a slightly shorter window period than a test that only detects antibodies.

equivalence trial

A clinical trial which aims to demonstrate that a new treatment is no better or worse than an existing treatment. While the two drugs may have similar results in terms of virological response, the new drug may have fewer side-effects, be cheaper or have other advantages. 

T cell

Also known as T lymphocytes, T cells are white blood cells that participate in a variety of cell-mediated immune reactions. Three fundamentally different types of T cells are recognized: helper, killer, and suppressor. CD4 cells are also known as T helper cells, whereas CD8 cells are one type of T killer cells. T cells are essential for a normal functioning immune system. The “T” stands for the thymus, where T-cells mature.

 

protease inhibitor (PI)

Family of antiretrovirals which target the protease enzyme. Includes amprenavir, indinavir, lopinavir, ritonavir, saquinavir, nelfinavir, and atazanavir.

nadir

Lowest of a series of measurements. For example, an individual’s CD4 nadir is their lowest ever measured CD4 count.

He tested proliferative responses to candida, tetanus toxoid, CMV, M.avium and HIV-1 p24 antigen, and found no difference in response, except for a better response to HIV-1 p24 in the treated group. DTH skin test reactions did not differ either, and CD4+ T cell subsets were similar too, except for evidence of more activated CD8+ cells in the untreated group.

References

Lederman M et al. Functional significance of CD4 cell numbers on the way down versus on the way up. Fifth International Congress on Drug Therapy in HIV Infection, Glasgow, abstract PL7.4, 2000.

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