Macrophages from HIV Cancer Victims Are Carcinogenic

A study has found that macrophages from HIV-infected lymphoma patients injected into severe combined immunodeficient (SCID) mice induced aggressive mouse T-cell lymphomas in the animals while macrophages from healthy donors did not. The study was published in the October 2002 issue of Cancer Research.

"This research establishes that macrophages can cause disease as opposed to current dogma, which asserts that the purpose of these cells is benevolent, solely to assist in fighting disease,” said the study's lead investigator, Dr. Michael S. McGrath, professor of laboratory medicine at the University of California, San Francisco (USA; www.ucsf.edu).

The investigators injected SCID mice lacking functional T and B lymphocytes with tumor cells from HIV-infected patients with a rare form of non-Hodgkin's lymphoma. Some mice were injected with macrophages and lymphoma cells together, some with macrophages separately, and some with lymphoma cells separately. A control group of SCID mice was injected with macrophages from healthy subjects.

Tumors developed in the mice injected with both macrophages and lymphoma cells from the HIV-infected lymphoma patients and in the mice injected with only the macrophages from the HIV-infected lymphoma patients. No tumors were found in the mice injected with only the lymphoma T-cells from the HIV-infected lymphoma patients, and none of the mice injected with normal human macrophages from healthy subjects developed lymphomas.

Dr. McGrath explained, "Our theory is that, during HIV infection, disease associated macrophages have HIV inserted near growth-promoting genes allowing macrophages to become neoplastic and begin to proliferate. These proliferating macrophages (pro macs) do what all macrophages do and produce factors. Normal macrophages produce factors to help fight diseases. Pro macs, instead, produce factors that stimulate lymphoma growth.”




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