Expression of T-cell activation marker CD134 (OX40) in lymphomatoid papulosis

CD134/OX40 and CD30 are transmembrane proteins from the tumour necrosis factor receptor (TNFR) family present selectively on activated T cells. TNFR-related proteins are crucially involved in the regulation of proliferation and survival of normal and malignant lymphohaematopoietic cells. CD30 has been used for the immunophenotyping and subclassification of cutaneous lymphomas; virtually nothing is known, however, about the expression pattern of CD134 in lymphoid skin malignancies.

To determine CD134 expression in cutaneous lymphoma and benign inflammatory disorders.

Biopsy material was obtained from patients with lymphomatoid papulosis (LyP, n = 42), mycosis fungoides (n = 21), Jessner's infiltrates (n = 10) and non-specific dermatitis (n = 14). The expression of CD134 and CD30 was scored after immunohistochemical staining with appropriate monoclonal antibodies. The proportion of G2 + S phase cells was determined by laser scanning cytometry from nuclei obtained from paraffin-embedded biopsies.

Few, single and scattered CD134+ cells (< 10%) were observed in the benign inflammatory infiltrations and in mycosis fungoides. A subset of 16 patients with LyP presented with clusters of CD30+ CD134+ cells. There was no correlation between the magnitude of CD134 expression and the histological type or the proportion of G2 + S cells in LyP. CD134 immunoreactivity was lower than expected in patients with LyP and another lymphoid malignancy (P < 0.001, Fisher's exact test).

CD134 is strongly expressed in a proportion (38%) of patients with LyP, but not in mycosis fungoides or benign lymphocytic infiltrations. Loss of CD134 expression in LyP may be a marker of an increased risk of second lymphoid malignancy.