Trichophytin reaction in natural and experimental dermatophytosis and in tuberculosis.

In a comparative study of the trichophytin reaction in 170 cases of ringworm and 571 subjects without apparent infection it was found that:1.Immediate reaction of urticarial type was very rare and non infiltrative erythema was not related to the presence of dermatophytes, occurring equally in both groups and independently of the result of delayed response.2.Delayed reactions could only be considered significant when strongly positive (infiltrative erythema with papules and vesicles, larger than 30 mm. in diameter), which appeared almost exclusively in cases of deep inflammatory ringworm.3.The presence of active tuberculosis or tuberculin sensitivity did not influence the response to trichophytin.4.Experimental inoculation with dermatophytes only modified trichophytin sensitivity when inflammatory lesions were produced.