Lack of Lysozyme Tied to HIV Dementia

By David Douglas

Patients with HIV who develop HIV-1-associated dementia appear to have lower levels of macrophage-secreted lysozyme, according to California-based researchers.

As senior investigator Dr. Lynn Pulliam told Reuters Health, "monocytes from individuals with HIV dementia do not release lysozyme, an enzyme, which is a major macrophage defense protein."

Such cells "normally secrete proteins that protect against bacteria and viruses and also produce other cytokines that may be defense mechanisms."

Dr. Pulliam and colleagues from the Veterans Affairs Medical Center, San Francisco, report in the April 30th issue of AIDS that using proteomics, they looked for differences in proteins secreted from monocytes in the blood of HIV-infected individuals with and without associated dementia, and from HIV negative controls.

Involved were 11 patients with associated dementia, 13 HIV seropositive patients without associated dementia, and 9 controls.

Secreted monocyte/macrophage levels of lysozyme were consistently lower in the associated dementia group (81 ng/mL) than in the HIV alone group (326 ng/mL) and the control group (764 ng/mL).

There was no correlation between viral load, CD4 cell count, use of highly active anti-retroviral therapy and lysozyme levels.

"This lack of a defense enzyme secretion," Dr. Pulliam concluded, "signals a nonfunctional monocyte/macrophage. Therapies--in addition to antiretroviral therapy--may be needed to boost normal monocyte/macrophage function."

AIDS 2004;18:1009-1012.