The effect of low dose chronic intermittent parental methotrexate on delayed type hypersensitivity and acute inflammation in a mouse model.

We have shown that a regimen of low dose intermittent methotrexate (MTX), analogous to that used in the treatment of patients with rheumatoid arthritis, does have immunosuppressive effects on the induction of primary delayed type hypersensitivity in normal mice. This occurred even when the last MTX injection was 4 days before immunization. No effect was seen on established delayed type hypersensitivity or on inflammatory responses induced by carrageenan or the Arthus reaction.