Multidrug resistance related proteins in primary cutaneous lymphomas

In patients with primary cutaneous B-cell lymphomas (CBCL) and primary cutaneous T-cell lymphomas (CTCL), extracutaneous sites may become involved and then polychemotherapy is indicated. Multi-agent chemotherapy may induce long lasting complete remissions in CBCL's. Most CTCL's, especially mycosis fungoides (MF), and CD30 negative primary cutaneous large T-cell lymphoma (PCLTCL) respond poorly or partially to Multi-agent Chemotherapy.

We have studied whether cutaneous lymphomas express the following multidrug resistance (MDR) related proteins: multidrug resistance protein (MRP), lung resistance protein (LRP) and P-glycoprotein (Pgp).

From the files of the Dutch Cutaneous Lymphoma Working Group we selected pretreatment punch biopsy specimens of the skin from 14 patients with MF, 10 patients with a PCLTCL and 8 patients with a CBCL. In several patients with a clinical relapse of their disease after multi-agent chemotherapy, punch biopsy specimens of cutaneous lesions were available (6 MF, 3 PCLTCL, 1 CBCL). Benign dermatoses with a dense lymphoid infiltrate were included as a control. Immunohistochemistry was done on formalin fixed, paraffin-embedded punch biopsy specimens with monoclonal antibodies MRPrl (anti-MRP); LRP-56 (anti-LRP); C219 (anti-Pgp). Staining was performed by the biotin-streptavidin immunoperoxidase method.

MRPrl staining was found in the cytoplasm of > or = 5%-50% of lymphoid cells in 13 out of 14 cases of MF and in 6 out of 10 patients with a PCLTCL. In 2 out of 8 cases of CBCL > or = 5%-50% positive tumorcells were found. Strong staining (> or = 50% of the cells positive) was found in 10 out of the total of 24 CTCL cases. LRP56 staining of lymphoid cells was found in 1 out of 14 cases of MF and in 1 out of 10 cases of PCLTCL and in 1 out of 8 cases of CBCL. C219 expression was found in 4 out of 10 cases of PCLTCL and in 2 out of 8 cases of CBCL. After chemotherapy both a higher staining intensity and a higher number of positive cells were found with MRPrl especially in patients with MF.

The present study shows that lymphoid cells in both primary cutaneous lymphomas and benign skin disorders may express MDR related proteins and that the expression profile of these proteins is roughly related to the tumor cell phenotype. However, the functional role of these proteins in clinical drug resistance in primary cutaneous lymphomas has to be proven.