Immunosuppressive Powers of the Antibacterial Agent Trimethoprim


THE antibacterial agent trimethoprim, 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine, is a competitive inhibitor of dihydrofolate reductase with an affinity for the bacterial enzyme about ten thousand times greater than that for the corresponding mammalian enzymes1,2. Its chemical similarity to dihydrofolate is not close, except that it has a pyrimidine ring which is also found in the widely used immunosuppressive agent azathioprine. Because of this feature, it was decided to test trimethoprim for immunosuppressive power in animals.

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GHILCHIK, M., MORRIS, A. & REEVES, D. Immunosuppressive Powers of the Antibacterial Agent Trimethoprim. Nature 227, 393–394 (1970).

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