Delayed hypersensitivity and differences of histologic pattern in allergic cutaneous vasculitis.

Fourteen patients with allergic cutaneous vasculitis of either the polymorphonuclear (PMN)- or the mononuclear (MN)-predominant type were studied as regards the following parameters: the disease duration, histology, monoclonal antibody typing of the mononuclear cell infiltrate from recent lesions, and the delayed hypersensitivity (DH) response, assessed both by recall antigens (tuberculin type) and the dinitrochlorobenzene skin test. From the results, it was shown that in PMN-predominant vasculitis, DH reactions were well elicited, whereas in MN-predominant vasculitis, DH skin reactions were somehow impaired. In MN-predominant cases, many OKT3+, OKT4+, OKT8+, and OKM1+ cells were usually seen to surround the skin vessels, whereas in PMN-predominant cases, rare OKT8+, OKT4+, or OKM1+ cells were seen in the dermis. The epidermal dendritic cell system, as revealed by the Na(1)34 monoclonal antibody, was unaffected in both types of allergic cutaneous vasculitis.