T cells and T-cell subsets in mycosis fungoides and parapsoriasis. A study of 18 cases with anti-human T-cell monoclonal antibodies and histochemical techniques.

Skin lesions from 15 patients with mycosis fungoides (MF) and from three with parapsoriasis were studied immunohistochemically with monoclonal antibodies against T cells (Leu 1) and against T-cell subsets (Leu 2a, Leu 3a). Lymphoid cell reactivity was diverse among these sampled cases. In two cases of parapsoriasis and nine of MF, there was a predominance of helper/inducer (Leu-3a-reactive) cells over suppressor/cytotoxic (Leu-2a-reactive) cells. In one case of parapsoriasis and one (advanced tumor stage) of MF, there was suppressor/cytotoxic cell predominance. One case of MF showed strong reactivity for both T-cell subset markers. Four cases of MF (two plaque-stage and two tumor-stage) featured a predominant cell type in the dermis which was nonreactive for all three antibodies. The intraepidermal lymphoid cellularity was Leu-1-reactive in ten cases of MF and two of parapsoriasis. Among these 12 cases, the intraepidermal cellularity was Leu-2a-reactive in four and Leu-3a-reactive in three. The use of such studies of T-cell subsets on in situ cutaneous lymphoid infiltrates may demonstrate a correlation with cytomorphology, clinical stage, and disease prognosis.