PRDT Infectivity Study Results Show Reduction in TSE Prions to Below Limit of Detection.

MONTREAL & LILLE, France -- ProMetic Life Sciences Inc. (TSX:PLI.SV)

Results Presented at 10th Annual TSE Conference Have Positive Implications for Human Blood Supply

Pathogen Removal and Diagnostic Technologies Inc. (PRDT), a joint venture between ProMetic Life Sciences Inc. (TSX:PLI.SV) and the American Red Cross, today announced that the results of its endogenous (blood-borne) infectivity study were presented by its lead scientific researcher, Dr Robert G. Rohwer, at the Cambridge Healthtech Institute's 10th Annual Transmissible Spongiform Encephalopathies Conference in Baltimore, MD.

The results show removal of blood-borne TSE (transmissible spongiform encephalopathy) infectivity from whole blood to below the limit of detection of the bioassay. TSEs are fatal brain diseases that include Bovine Spongiform Encephalopathy (BSE) or "mad cow disease" in cattle and variant Creutzfeldt - Jakob disease (vCJD) in humans.

Technology removes prions from whole blood

Dr. Rohwer's laboratory was able to demonstrate a greater than 10 fold reduction in titer even at the very low concentrations of endogenous infectivity in whole blood. Based on the current knowledge that TSE infections can occur well beyond a year of incubation, all lab animals (hamsters) were held for 550 days, when they begin to die of old age. The animals were injected with leukoreduced scrapie  infected whole blood and those which received blood previously filtered through devices containing the PRDT resin did not develop signs of the disease.

To detect any infections that might be incubating at the end of the experiment, the brains of all animals were tested for the presence or absence of the abnormal form of the prion protein. There was no detectable abnormal prion protein in any of the 100 animals inoculated with the blood that had been filtered through the PRDT affinity resin confirming the complete absence of TSE disease.

"We are extremely pleased with the successful outcome of this extensive endogenous study and believe that the study results have positive implications for the safety of human blood supply.

It is important to remember that even though the concentration of TSE infectivity in blood and red blood cells is very low, the exposure from a transfusion of infected blood is greatly amplified due to the volumes that are typically administered", said Dr. Robert G. Rohwer, professor at the University of Maryland at Baltimore and the principal researcher on the study.

The results of the study are expected to be published later this year by PRDT, Dr. Robert G. Rohwer, professor at the University of Maryland at Baltimore and Dr. Luisa Gregori, the principal researcher on the study.

About the study

PRDT has already demonstrated that several of its resins are capable of removing 99.9% to 99.99% of a high concentration of TSE infectivity prepared from brain when spiked into human red blood cells (RBC). While the brain contains very high concentrations of infectivity, there is growing evidence that the form of the infectivity in blood may not be well represented by that isolated from the brain.

In order to test whether its lead prion binding resin would also adsorb the endogenous infectivity found in blood, PRDT undertook an extensive "endogenous" experiment.A major challenge to the design of this experiment was the low concentration of TSE infectivity in whole blood (approximately 10 infectious doses per ml) which is one billion times smaller than found in the brain.The infectivity associated with blood depleted of its whitecells - now a standard practice in the preparation of red cells for transfusion - is half that of whole blood with the remaining infectivity found largely in the plasma component.

The initial application of the PRDT prion-binding affinity resin will be the reduction of TSE infectivity from red blood cells (RBC). Since 80 to 90% of the plasma is removed during preparation of RBC, the remaining infectivity could be as low as 0.5 to 1 infectious dose (ID)/ml.To demonstrate the highest possible level of removal, PRDT tested its prion binding resin with infected leukoreduced whole blood instead of RBC.The titer was ten to twenty times higher than expected for RBC due to the presence of the entire plasma component. Furthermore, removal of prion infectivity from whole blood to the limit of detection indicates the PRDT prion-binding resin has excess adsorptive capacity relative to that required for prion capture from RBC concentrate, demonstrating its potential suitability for TSE reduction from whole blood as well as RBC.

Using the highly sensitive and precise "limiting dilution" method of titration of TSE infectivity developed in Dr. Rohwer's laboratory, PRDT was able to demonstrate slightly greater than a 10 fold reduction in titer even at these very low concentrations of endogenous infectivity.From prior experience with the limiting dilution method, where infections can occur well beyond a year of incubation, all animals were held for 550 days (when they begin to die of old age).

In PRDT's first infectivity study, it was established that the selected affinity resins were capable of removing very high concentrations of TSE infectivity, far in excess of concentrations that have so far been detected in blood.In the ensuing "endogenous" experiment, PRDT has successfully demonstrated that its lead resin also adsorbs and removes the specific form of TSE infectivity that is found at very low concentration in blood.

The study was co-sponsored by PRDT and its manufacturing and commercial partner, MacoPharma, a European industry leader in blood collection systems and transfusion solutions. PRDT's resin, which is incorporated into the MacoPharma prion filter,P-CAPT(TM), is the first to demonstrate reduction of TSE prions from whole blood.

About PRDT

PRDT is a joint-venture company set up in March 2002 by The American National Red Cross, ProMetic Life Sciences Inc., ProMetic BioSciences Ltd, Dr. Robert G. Rohwer and Dr Ruben G. Carbonell. PRDT allows for a reciprocal exchange of technology and a knowledge base developed between the American Red Cross and ProMetic. PRDT's main goal is to develop products and devices to remove and detect different pathogens from biological sources. This research augments work that ProMetic, the American Red Cross and PRDT's scientific founders have been conducting independently for many years.

About MacoPharma

MacoPharma is an innovator in global healthcare with expertise in the fields of transfusion and infusion. The Company has become the largest supplier of in-line leukoreduction filtration sets in Europe and is expanding its efforts into the biotherapy field by developing products for cell expansion, in addition to cell/organ processing and freezing. Headquartered in the Lille metropolitan area (France), MacoPharma has three manufacturing facilities in Europe and its products are now sold into more than 55 countries worldwide. One of MacoPharma's aims is to provide a comprehensive range of products for the reduction of infectious agents in plasma, platelets and red cells. This is consistent with MacoPharma's strategy to develop products through partnerships, for improved safety, efficacy, and quality of transfusion, infusion and biotherapy. For more information please contact: www.macopharma.com

About ProMetic Life Sciences

ProMetic Life Sciences Inc. (TSX: PLI.SV) is a biopharmaceutical company specialized in the research, development, manufacture and marketing of a variety of commercial applications derived from its proprietary enabling technology. Mimetic LigandTM technology is used in large-scale purification of biologics and the elimination of pathogens. ProMetic is also active in therapeutic drug development with the mission to bring to market effective, innovative, lower cost, less toxic products for the treatment of inflammation and cancer. ProMetic's drug discovery activities also aim at replacing complex, expensive proteins with synthetic "drug-like" protein mimetics. Headquartered in Montreal (Canada), ProMetic has R&D and manufacturing facilities in the UK and business development activities in the US, Europe, Asia and countries in the Middle East and North Africa. Additional information is available on the ProMetic's website: www.prometic.com.

Forward-Looking Statements

This press release contains forward-looking statements about ProMetic and PRDT's objectives, strategies and businesses that involve risks and uncertainties. These statements are "forward-looking" because they are based on current expectations about the markets they operate in and on various estimates and assumptions. Actual events or results may differ materially from those anticipated in these forward-looking statements if known or unknown risks affect their businesses, or if such estimates or assumptions turn out to be inaccurate. Such risks and assumptions include, but are not limited to,ProMetic's and PRDT's ability to develop, manufacture, and successfully commercialize value-added products, the availability of funds and resources to pursue R&D projects, the successful and timely completion of clinical studies, the ability of ProMetic to take advantage of business opportunities in the pharmaceutical industry, uncertainties related to the regulatory process and general changes in economic conditions. You will find a more detailed assessment of the risks that could cause actual events or results to materially differ from ProMetic's current expectations on page 15 ofProMetic's Annual Information Form for the year ended December 31, 2004, under the heading "Risk Factors". As a result, we cannot guarantee that any forward-looking statement will materialize. We assume no obligation to update any forward-looking statement even if new information becomes available, as a result of future events or for any other reason.

ProMetic Life Sciences Inc. (TSX:PLI.SV)