Photo/IllutrationTears contain a fatty compound that could be used to develop new drugs for organ transplants.(The Asahi Shimbun file photo)

A fatty compound found in animal tears could be used to develop new drugs to prevent the human body from rejecting transplanted organs, according to researchers.

The team of researchers from Kyushu University, Keio University and other institutions discovered that cholesterol sulfate, a type of lipid found in mice tears, suppresses immune cells in eye tissue. The compound was largely found in the tissues that supply the lipid to the eyes.

“A part of the secret of how living things evade the immune system is now unraveled,” said team leader Yoshinori Fukui, a distinguished professor of immunogenetics at the Medical Institute of Bioregulation of Kyushu University. “We hope the findings will lead to the development of a new treatment or drugs.”

The team produced “designer” mice with tear glands that cannot produce cholesterol sulfate. When those mice were exposed to ultraviolet rays, the amount of immune cells on their eyeballs increased more than in regular mice.

When cholesterol sulfate was topically applied to the eyes of the designer mice, the amount of immune cells dropped to a level close to that of regular mice.

The compound suppresses inflammation of the eyeballs caused by the immune system, thus preventing clouding of them, according to the team.

The lipid may make deliberate control of the activity level of immune system possible and could lead to the development of a new method for suppressing immunological rejection of transplanted organs.

The paper was published in the U.S. academic journal Science Signaling on July 31.