Differential expression of the HECA‐452 antigen (cutaneous lymphocyte associated antigen, CLA) in cutaneous and non‐cutaneous T‐cell lymphomas

Abstract

The monoclonal antibody HECA‐452 identifies an antigen that is primarily expressed on high endothelial venules, the preferred site of lymphocyte extravasation in lymphoid tissues, and also on a subpopulation of myelomonocytic cells and some T‐cells. We investigated the expression of the HECA‐452 antigen, also called the cutaneous lymphocyte associated antigen, in primary cutaneous and primary non‐cutaneous T‐cell non‐Hodgkin's lymphomas. The tumour cells of cutaneous T‐cell non‐Hodgkin's lymphomas were positive in 53% of cases, while only 5% of the non‐cutaneous lymphomas were positive. These differences were also present in morphologically identical tumours. Thus, the tumour cells in six cut of 10 primary cutaneous anaplastic large cell T‐cell lymphomas were positive, while they were positive in none of 24 primary non‐cutaneous anaplastic large cell T‐cell lymphomas. In general, primary cutaneous and primary nasal T‐cell non‐Hodgkin's lymphomas were devoid of HECA‐452 positive high endothelial venules, whereas most nodal T‐cell non‐Hodgkin's lymphomas contained HECA‐452 positive high endothelial venules. These observations suggest that the HECA‐452 antigen might be related to a skin‐associated type of lymphoid tissue and to lymphomas originating in the skin. However, the results of HECA‐452 expression in secondary sites, and the clinical data of the primary cutaneous large cell lymphomas did not support the concept that HECA‐452 is functionally involved in homing to the skin, or that loss of the HECA‐452 antigen is related to tumour progression of primary cutaneous T‐cell lymphomas. The differences in HECA‐452 expression do indicate, however, that the dissimilar clinical behaviour of primary cutaneous and non‐cutaneous T‐cell non‐Hodgkin's lymphomas might be related to differences in expression of homing and adhesion molecules.