PRNewswire - October 14, 1999

The study examined immune responses elicited by HIV-specific antigens (HIV particles recognized by the body as being foreign) in order to identify and characterize those responses associated with AIDS-free status. Specifically, beta-chemokine (RANTES, MIP-1alpha and MIP-1beta) production and lymphocyte proliferation were measured in blood samples from 100 HIV-positive patients. In order to test whether these responses were directed specifically against HIV, the antigens HIV-1 (whole-killed, envelope depleted HIV) and p24 (protein from core of HIV) were used to stimulate the blood samples. Lymphocyte proliferation to HIV-1 (p=0.004) and p24 (p=0.001) was significantly stronger in asymptomatic patients compared to AIDS patients. In addition, higher levels of both HIV-1 antigen-stimulated beta-chemokines, MIP-1alpha (p=0.038) and MIP-1beta (p=0.004), but not the beta-chemokine RANTES, were observed in asymptomatic patients compared to AIDS patients.

"These results support the possibility that production of certain chemokines and lymphocyte proliferation are important immune responses elicited by HIV-specific antigens and may play a role in controlling HIV infection," said Ronald B. Moss, M.D., executive director of medical and scientific affairs of The Immune Response Corporation and co-author of the PNAS article. The study also showed that increased beta-chemokine (MIP-1alpha and MIP-1beta) production was correlated with enhanced lymphocyte proliferation to HIV-specific antigens (r=0.475, p=0.001). Since beta- chemokines are produced mainly by activated T-cells, the observed correlation suggests that enhanced chemokine production may be dependent on T-cell expansion.

"The Company is pleased with these results because previous studies of our proprietary immune-based therapy Remune(TM), which is under development, have shown enhancement of both beta-chemokine production and lymphocyte proliferation to the same HIV-specific antigens used in the current study," said Dennis J. Carlo, Ph.D., The Immune Response Corporation's president and chief executive officer.

HIV normally gains entry into CD4 T-lymphocytes, the cells targeted for destruction by HIV, by attaching to molecules known as receptors and coreceptors present at the cell surface. The beta-chemokines, such as RANTES (regulation-on-activation, normal T cell expressed and secreted) and MIPs (macrophage inflammatory proteins), assist the immune response to HIV by binding to certain CD4 coreceptors and physically blocking the entry of the virus, thereby preventing the HIV invasion. Therefore, stimulating beta- chemokine production, an effect observed after treatment with Remune(TM), could potentially help block the spread of HIV into uninfected cells.

Lymphocyte proliferation, the replication of T-cells in response to an antigen, is an immunologic marker of disease progression. These responses are lost early in the course of HIV infection. Interestingly, strong lymphocyte proliferative responses are characteristic of HIV-infected people who do not develop the AIDS syndrome (long-term nonprogressors).

The Immune Response Corporation is a biopharmaceutical company based in Carlsbad, California, developing immune-based therapies to induce specific T- cell responses for the treatment of HIV and autoimmune diseases. In addition, the Company is working on cancer vaccines and gene therapy.

NOTE: News releases are available through PR Newswire Company News On-Call fax service. For a menu of available news releases or to retrieve a specific release made by The Immune Response Corporation, please call 800-758-5804, extension 434675. Please retain this number for future reference. Company information can also be located on the Internet Web Site: http://www.imnr.com.

This news release contains forward-looking statements. Actual results could vary materially from those expected due to a variety of risk factors, including, but not limited to whether there is an association between high levels of beta-chemokines, lymphocyte proliferation and a more favorable clinical status in AIDS of HIV infected individuals, whether REMUNE would enhance beta-chemokine and lymphocyte proliferation, whether enhancements would help block the spread of HIV into infected cells and whether REMUNE will be successfully developed and approved for marketing. These and other factors are discussed more thoroughly in The Immune Response Corporation's SEC filings, including but not limited to its report on Form 10-K for the year ended December 31, 1998 and subsequent Forms 10-Q. The Company undertakes no obligation to publicly release the result of any revisions to these forward- looking statements which may be made to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events.

Remune(TM) is a trademark of The Immune Response Corporation.

SOURCE The Immune Response Corporation

CONTACT: Dennis J. Carlo, Ph.D., President and Chief Executive Officer of The Immune Response Corporation, 760-431-7080/
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