SAN DIEGO, July 1, 2002 -- La Jolla Pharmaceutical Company (Nasdaq: LJPC) today announced that the Company presented previously released data concerning LJP 394 and LJP 1082, the Company's drug candidates for the treatment of antibody-mediated autoimmune diseases, at the Federation of Clinical Immunology Societies (FOCIS) Second Annual Meeting on June 30, 2002 in San Francisco.

Andrew Wiseman, Ph.D., Senior Director of Business Development at La Jolla Pharmaceutical Company, presented a poster summarizing data from a double-blind, placebo-controlled Phase II/III trial of more than 200 lupus patients that evaluated LJP 394, the Company's therapeutic compound for the treatment of lupus kidney disease. In the 89% of patients in the trial with high-affinity antibodies for the drug, treatment with LJP 394 prolonged time to and decreased the number of renal flares, the primary endpoint of the trial, and delayed the need for and decreased the number of high-dose corticosteroid and/or cyclophosphomide treatments when compared to placebo. A Phase III clinical trial is being conducted to confirm these results.

Keith Cockerill, Ph.D., Associate Director of Research at La Jolla Pharmaceutical Company, gave an oral presentation summarizing data from in vivo studies of LJP 1082, the Company's innovative approach to treating antibody-mediated thrombosis. Previous data confirmed that disease-causing antibodies from patients with antibody-mediated thrombosis bind primarily to domain 1 of beta 2 glycoprotein 1, a protein involved in blood clotting. In an immunized rat model, treatment with LJP 1082 reduced levels of disease-causing antibodies and the B cells that produce them. The data indicate that treatment of antibody-mediated thrombosis patients with a B cell Toleragen® such as LJP 1082 could reduce antibodies associated with an increased risk of thrombotic events without the bleeding risk associated with current anticoagulation therapies. A Phase I/II clinical trial of LJP 1082 is being conducted in patients with antibody-mediated thrombosis.

About antibody-mediated autoimmune diseases
Antibody-mediated autoimmune diseases occur when the immune system's B cells, which normally generate antibodies that fight disease, produce disease-causing antibodies that attack otherwise healthy cells. Lupus and antibody-mediated thrombosis are two of the most common antibody-mediated autoimmune diseases. Lupus affects approximately one million patients the United States and Europe, and antibody-mediated thrombosis affects as many as two million patients.

Lupus (Systemic Lupus Erythematosus)
Lupus is an autoimmune disease that results in a wide variety of chronic, progressive symptoms including episodes of life-threatening kidney inflammation known as "renal flares." The current standard of care for lupus - treatment with steroids and chemotherapy drugs - causes severe side effects including diabetes, hypertension and sterility and leaves patients vulnerable to potentially lethal opportunistic infections. LJP 394 is designed to specifically prevent the production of antibodies responsible for lupus kidney disease without suppressing the normal functions of the immune system.

Antibody-Mediated Thrombosis (Antiphospholipid Syndrome)
Antibody-mediated thrombosis is a severe blood-clotting disorder that results in an increased risk of stroke, deep-vein thrombosis, heart attack, recurrent miscarriage and heart valve lesions. Patients often experience their first stroke, heart attack or miscarriage in their 20s and 30s, and studies indicate they have twice the probability of a recurrence. Current treatments include anticoagulants, which are difficult to accurately prescribe and with long-term use can lead to side effects including life-threatening bleeding events. LJP 1082 is the first product specifically designed to treat antibody-mediated thrombosis.

La Jolla Pharmaceutical Company is a biotechnology company leading the development of therapeutics for antibody-mediated autoimmune diseases afflicting several million people in the United States and Europe. The Company is conducting a Phase III trial of LJP 394 in patients with lupus kidney disease, a leading cause of sickness and death in these patients. The Company is also conducting a Phase I/II trial of LJP 1082 for the treatment of antibody-mediated thrombosis, a condition in which patients suffer from recurrent stroke, deep-vein thrombosis and other thrombotic events. The Company's common stock is traded on The Nasdaq Stock Market under the symbol LJPC. For more information about the Company, visit our Web site: http://www.ljpc.com. Patients interested in the Phase III lupus trial may call 1-800-30-LUPUS for information.

Except for historical statements, this press release contains forward-looking statements involving significant risks and uncertainties, and a number of factors, both foreseen and unforeseen, could cause actual results to differ materially from our current expectations. Our analyses of clinical results of LJP 394, our drug candidate for the treatment of systemic lupus erythematosus ("lupus"), and LJP 1082, our drug candidate for the treatment of antibody-mediated thrombosis ("thrombosis"), are ongoing and future analyses could result in a finding that these drug candidates are not effective in large patient populations, do not provide a meaningful clinical benefit or may reveal a potential safety issue requiring us to develop new candidates. Our blood test to measure the binding affinity for LJP 394 is experimental, has not been validated by independent laboratories, may require regulatory approval and may be necessary for the approval and the commercialization of LJP 394. Our other potential drug candidates are at earlier stages of development and involve comparable risks. Analysis of our clinical trials could have negative or inconclusive results. Any positive results observed to date may not be indicative of future results. Even if results are promising, the U.S. Food and Drug Administration ("FDA") may require additional clinical trials. The Company's ability to develop and sell its products in the future may be affected by the intellectual property rights of third parties. Additional risk factors include the uncertainty of: obtaining required regulatory approvals; successfully marketing products; receiving future revenue from product sales or other sources such as collaborative relationships; future profitability; the need for additional financing; our dependence on patents and other proprietary rights; FDA approval of our manufacturing facilities; the increase in capacity of our manufacturing capabilities for possible commercialization; and our lack of marketing experience. Readers are cautioned to not place undue reliance upon forward-looking statements, which speak only as of the date hereof, and we undertake no obligation to update forward-looking statements to reflect events or circumstances occurring after the date hereof. Interested parties are urged to review the risks described in our other reports and registration statements filed with the Securities and Exchange Commission from time to time, including the report on Form 10-K for the year ended December 31, 2001.