抄録
Cheyletus forsis Oudemres, a predacious mite of the family Cheyletidae, caused itchy dermatitis on the arms of 5 out of 12 volunteers 24hr after the application of 6 live mites, consisting of 5 Cheyletus fortis (C.f.) and one Tyrophagus putrescentiae (Schrank)(T.p.), for each person. These mites were applied to the small closed area of the skin separately for 24hr. On the areas where T.p. were applied, no lesions were observed. The lesions, caused by C.f., varied from slightly edematous erythema of 2 to 3mm in diameter to highly edematous erythema with central vesiculation of 7 to 8mm, depending on the sensitivity of the volunteers to the mites. The biopsy specimen revealed epidermal spongiosis, intraepidermal spongiotic vesicles, subepidermal edema and perivascular lymphohistiocytic infiltration with eosinophils, and corresponded to that of allergic contact dermatitis, the IV type of allergy. The results of the closed patch test on the normal skin of the same volunteers using the homogenate of C.f. and T.p. were almost negative. But, on the test sites, where cornified layer were previously peeled off with Scotch tape, positive reactions were obtained 24hr after the application of the C.f. homogenate for 9 volunteers out of 12. These results mean that C.f. causes dermatitis in man and this mechanism is based on the IV type of allergy. The antigen of C.f. is supposed to be high molecular substance which can not pass through the stratum corneum.
