In dermatophytosis, there is exocytosis of polymorphonuclear leukocytes (PMNs) toward the fungus-laden horny layer. To analyze this mechanism, we studied in vitro leukotactic properties of epidermal extracts prepared from lesions of experimental Trichophyton mentagrophytes infection in guinea pigs as well as fungus-derived chemotactic factors. Trichophyton mentagrophytes was found to release low-molecular-weight PMN chemotactic factors with its growth, like other microorganisms. Furthermore, it activated complement via the alternative pathway to produce complement-derived chemotactic factors in vitro. The epidermal extracts prepared from weakly inflammatory lesions of an early stage of T. mentagrophytes infection showed mild PMN chemotactic activity, which, as in those from irritated skin, was mostly due to the presence of low-molecular-weight chemotactic factors. After 8 days of infection, when prominent PMN migration took place together with the development of immune reactivity to fungus antigens, the epidermal extracts revealed strong leukotactic activity that showed a triphasic pattern by Sephadex G-75 chromatography similar to that observed in complement-activated serum. Since we could not demonstrate any deposition of immunoglobulins and complement on the fungal elements present in the horny layer, actual complement activation in vivo seems to occur after interaction of serum with soluble fungal components in the epidermis through both classic and alternative pathways. We think that the transepidermal migration of PMNs in dermatophytosis, together with contact sensitivity to fungal antigens, is responsible for induction of increased epidermopoiesis with resultant desquamation to eliminate the fungus-laden horny layer.

Contact sensitization was achieved with dinitrophenylated autologous lymph node cells killed by hypotonic lysis or sonication as well as live cells. The sensitizing ability of the sonicated cells disappeared after freeze-thawing or heating. The significance of these findings is discussed.

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The number of DNP group-bearing lymphocytes in the regional lymph node, thoracic duct and peripheral blood was determined at various time intervals after painting normal guinea pigs with DNCB by the immunofluorescent method using anti-DNP antibody. The incidence of such cells in the regional node was maximal at 12 hours whereas in the thoracic duct and peripheral blood the maximum incidence was found at 0.1-2 hours after painting. Unreacted DNCB was demonstrated in both the thoracic lymph duct and the blood at least for 12 or 24 hours respectively following exposure to DNCB. The authors therefore suggest that DNCB reacts directly in vivo with the lymphocyte cell membrane of guinea pig following epicutaneous application of the chemical.

A Japanese girl aged 15 months had an eruption of 3 months’ duration on the face, trunk, and extremities except for the palms and soles. The lesions were infiltrated papules varying from 2 to 3 mm in diameter. Blood eosinophilia of 5% was demonstrated. Skin biopsy specimen revealed a necrobiotic palisading granuloma in the corium. All lesions began to subside after 1 weeks’ administration of oral corticosteroid and completely involuted in 2 months. A possible etiologic role of insect bites was considered.