WALKERSVILLE -- BioWhittaker Inc. said yesterday that it filed a lawsuit charging patent infringement against Procordia AB, four Procordia subsidiaries and a customer of Procordia.

BioWhittaker, based in Frederick County, said it is seeking unspecified damages and payment of "all gains, profits, and advantages derived from the defendant's infringement of the patent."

It said the companies infringed on a patent covering a blood test that diagnoses allergies.

The lawsuit, filed in U.S. District Court in Virginia, names Stockholm-based Procordia and its subsidiaries, Pharmacia USA Inc., Pharmacia Biotech Inc., Pharmacia Diagnostics AB and Kabi Pharmacia Inc. Also named was American Medical Laboratories, a Chantilly, Va.-based customer of Procordia.

The lawsuit charges that the defendants were and still are willfully participating in the manufacture and sale of products based on BioWhittaker's patented technology.

BioWhittaker makes cell culture products, clinical diagnostic testing systems, and endotoxin assays for health-care and biotechnology markets.

Its stock closed yesterday at $6.375, up 25 cents, on the Nasdaq.