Cutaneous Hypersensitivity and Desensitization to Mechlorethamine in Patients with Mycosis Fungoides Lymphoma

Abstract

Eleven of sixteen consecutive patients with mycosis fungoides lymphoma became allergically sensitized to topical applications of mechlorethamine (nitrogen mustard or HN2) used as treatment of their disease. This sensitization was shown to be of the delayed hypersensitivity type, as judged by; the typical clinical appearance of allergic contact dermatitis; the time intervals required for sensitization to occur and for challenge tests to react; the histopathologic features of the cutaneous reaction; the elicitation of responses to doses as low as 1/50,000 of early test doses which had caused no reactions; and the passive transfer of sensitivity to a non-sensitized recipient by intradermally injected leukocytes from a reactive donor. The antigenic specificity of the contact allergy to HN2 was investigated by patch tests with 4 other nitrogen mustards containing bis([beta]-chloroethyl) groups; no cross-reactivity was demonstrated. Even parenterally-administered cyclo-phosphamide failed to evoke allergic reactions. Six of 8 patients sensitive to HN2 topically did not react allergically to its parenteral administration. Introduction of various degrees of cutaneous unre-sponsiveness to HN2 was accomplished by intravenous administration of small doses of the drug in these 6 patients. This unresponsiveness appeared to be specific for HN2 inamuch as contact allergy to dinitro-chlorobenzene was unaffected.