CHICAGO -- Ten people, including four doctors, have been charged with swindling insurance companies out of more than $1.5 million by providing hundreds of patients with allergy shots without proper testing and sometimes under unsanitary conditions, prosecutors announced Thursday.

The indictment returned Wednesday alleges that some patients received the shots without being tested to determine if they were needed and some received shots without being warned about the risks involved.

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Blood tests were sometimes not sent to the laboratory until the insurance company paid, by which time the blood was no longer in proper condition to reveal allergies, according to the indictment. Shots also were selected, prepared and administered by unqualified people under unsanitary conditions, the indictment said, though it did not detail those conditions.

No medical problems have been reported as a result of the shots, federal officials said.

Before making the indictment public, federal agents on Thursday morning arrested two of those charged, John Froelich, 49, of suburban Harwood Heights, and Paul Kocourek, 53, of Chicago.

Prosecutors said Froelich operated and controlled several companies that provided the allergy shots, chiefly the American Institute of Allergy, which did business in Illinois, northwestern Indiana and Arizona.

All those involved in the alleged scam were affiliated with Froelich businesses, it said. Kocourek worked for American Institute of Allergy and submitted bogus claims to insurance companies, according to the indictment.

Froelich and Kocourek appeared in federal court Thursday afternoon; each was released on $100,000 unsecured bond. The other defendants are to receive summonses for later hearings.

Froelich attorney Joseph J. LaRocco had no comment on the charges. Kocourek attorney Michael I. Leonard said: "We strongly believe in his innocence but our investigation is just beginning."