Cutaneous T cell lymphoma: immunocytochemical study on activation/proliferation and differentiation associated antigens in lymph nodes, skin, and peripheral blood

Interleukin-2 fusion toxin: targeted therapy for cutaneous T cell lymphoma

The interleukin (IL)-2 receptor has proved an attractive target for T cell-directed therapies. Agents including monoclonal antibodies, single-chain antibody immunoconjugates, radioimmunoconjugates, and, most recently, ligand fusion toxins have demonstrated activity in vitro and in clinical trials in both hematologic malignancies and diseases characterized by proliferation of activated T cells, such as graft-versus-host disease. DAB389IL-2 (ONTAK) is a ligand fusion toxin consisting of the full-length sequence of the IL-2 gene genetically fused to the enzymatically active and translocating domains of diphtheria toxin. DAB389IL-2 and its predecessor, DAB486IL-2, have demonstrated activity in a variety of diseases, including cutaneous T cell lymphoma (CTCL), psoriasis, rheumatoid arthritis, and HIV infection. Further clinical development of IL-2 fusion toxins in CTCL and other hematopoietic malignancies is predicated on identification of the high-affinity IL-2 receptor complex on the malignant cells and on a better understanding of the biological determinants of cytotoxicity of these molecules in vivo.

DAB(389)IL-2 (ONTAK): a novel fusion toxin therapy for lymphoma

Fusion proteins are recombinant molecules that combine a targeting mechanism to a cytocidal moiety. DAB(389)IL-2 (denileukin diftitox; ONTAK), with a unique mechanism of action, is the first genetically constructed fusion protein to reach the clinic. In this molecule, the interleukin-2 (IL-2) gene is genetically fused to the enzymatically active and translocating domains of diphtheria toxin. DAB(389)IL-2 is internalized into IL-2 receptor-bearing cells by endocytosis. The ADP-ribosyltransferase activity of diphtheria toxin is cleaved in the endosome and is translocated into the cytosol where it inhibits protein synthesis, leading to apoptosis. DAB(389)IL-2 and its predecessor, DAB(486)IL-2, have shown clinical activity in a variety of diseases, including B-cell non-Hodgkin's lymphoma, cutaneous T-cell lymphoma (CTCL), Hodgkin's disease, psoriasis, rheumatoid arthritis, and HIV infection. The highest response rates were observed in CTCL, and this became the focus of clinical trials leading to its subsequent approval by the United States Food and Drug Administration for this disease. The potential applications of DAB(389)IL-2 in lymphomas are reviewed.

Mycosis fungoides with CD30-positive cells in the epidermis

Large numbers of CD30-positive tumor cells are not typically observed in mycosis fungoides (MF), but CD30 expression may occur on large cells of MF that have transformed into high-grade large cell lymphoma. Of 202 patch/plaque phase MF cases studied by immunohistochemistry, we encountered 4 patients with patch-phase MF at stage Ia or Ib, whose lesions contained a high proportion (greater than 50%) of CD30-positive tumor cells within the epidermis. The morphologic and immunohistochemical features of these four cases were otherwise similar to those of other patch-phase MF cases, and were different from those of pagetoid reticulosis. More importantly, the clinical behavior of these cases did not differ from that of other cases of early MF without CD30 expression. The mechanism underlying the high levels of CD30 expression by epidermotropic tumor cells is unknown. With increased use of the CD30 immunohistochemical stain in the diagnosis of cutaneous lymphomas, similar cases are likely to be encountered, and perhaps will be evaluated for their clinical behavior.

Quantitation of intraepidermal T-cell subsets in formalin-fixed, paraffin-embedded tissue helps in the diagnosis of mycosis fungoides

Differentiation between mycosis fungoides (MF) and cutaneous inflammatory processes can usually be made on clinical and histologic grounds. In difficult cases, immunohistochemical studies can be helpful since MF infiltrates usually contain a predominance of CD4+ lymphocytes, while most inflammatory lesions usually have a mixture of CD4+ and CD8+ lymphocytes. However, this determination has traditionally required the use of frozen tissue, thus severely limiting its usefulness. Recently, antibodies that differentially label CD4+ and CD8+ lymphocytes in formalin-fixed, paraffin-embedded tissue have become available (OPD4 and C8/144B respectively, DAKO (Carpinteria, CA, USA). This study tests the utility of these antibodies in the pathologic diagnosis of MF and inflammatory lesions with significant exocytosis. In 9 cases of MF for which both frozen and fixed tissues were available for comparison, the OPD4+ cell count in fixed tissue was significantly lower than the Leu-3a+ cell count in frozen tissue. Also, the C8/144B+ cell count in fixed tissue was higher than the Leu-2a+ cell count in frozen tissue, although this difference was not significant statistically. In a larger series for which only fixed tissue was available, epidermal CD4:CD8 ratios were significantly greater in 23 MF cases (mean 4.0+/-4.76) than in 35 inflammatory cases (mean 0.6+/-0.42; p = 0.001). Thus, although the studied antibodies appear to detect different epitopes in frozen versus paraffin-embedded tissue, demonstration of an elevated CD4:CD8 ratio in fixed tissue supports the diagnosis of MF, and is a helpful adjunct to routine histopathology.

Correlation between clonotypic T-cell receptor beta chain variable region (TCR-V beta) gene expression and aberrant T-cell antigen expression in cutaneous T-cell lymphoma

Immunohistochemical studies can augment the clinicopathologic diagnosis of cutaneous T-cell lymphoma (CTCL). Our goal was to determine whether a panel of 11 T-cell receptor (TCR) beta chain variable region (V beta) monoclonal antibodies (moAbs) could consistently identify clonal T-cell populations within CTCL skin infiltrates, and whether these cell exhibited aberrant T-cell antigen expression. Biopsies from 24 CTCL and 3 parapsoriasis patients were analyzed. Of the 27 patients, 4 (15%) demonstrated T-cell clonality by restricted TCR-V beta moAb staining. The V beta + restricted cells expressed aberrant antigen profiles. Overall, aberrant antigen profiles were detected in 18/24 (75%) CTCL. Patients. V beta 18 moAb crossreacted with a 85 kD protein produced by basal and suprabasal keratinocytes. We conclude: 1) Restricted TCR-V beta expression correlated with aberrant T-cell antigen profiles: 2) In the absence of a complete panel of TCR-V beta moAbs, localization of aberrant T-cell antigen expression can be useful in identifying malignant T-cells within CTCL skin infiltrates; 3) The detection sensitivity and specificity of the currently available TCR-V beta moAbs may limit their utility to consistently detect clonal T-cell populations in CTCL skin biopsies; 4) A 85 kD protein present on basal and suprabasal keratinocytes is recognized by V beta 18 moAb and may be related to immune function(s) of the epidermis.

T-cell lymphoma cell lines (HUT102 and HUT78) established at the National Cancer Institute: history and importance to understanding the biology, clinical features, and therapy of cutaneous T-cell lymphomas (CTCL) and adult T-cell leukemia-lymphomas (ATLL)

Efforts at the National Cancer Institute to generate continuous in vitro cultures from patients with mycosis fungoides and the Sezary syndrome, neoplasms with a mature T-helper phenotype, led to the establishment of two cell lines, HUT78 and HUT102. Further characterization of these cell lines led to the identification of the first human retrovirus, HTLV-1, in the HUT102 cells, and the clinical description of the syndrome of HTLV-1 associated acute T-cell leukemia/lymphoma; the serum antibody test to screen for this virus was developed from the serum of the patient from whom the cell line was derived. The HUT78 cell line was pivotal in the identification and characterization of the HIV retrovirus in that a subclone, H9, proved to be permissive for replication of HIV in vitro. Propagation of HIV in vitro in H9 cells allowed for the development of immunological reagents to screen blood supplies for the presence of the virus. Further biologic and molecular studies of these lines have led not only to a better understanding of the underlying diseases but also to the development of rational therapeutic approaches.

A multidisciplinary approach to the diagnosis of cutaneous T-cell lymphomas

The cutaneous T-cell lymphomas (CTCLs) comprise a spectrum of non-Hodgkin lymphomas with a predilection for the skin. This heterogeneous group of CTCLs include the prototypic CTCL mycosis fungoides (MF) and the recently described Ki-1+ lymphomas. MF is notoriously difficult to diagnose in its early stages. The histologic appearance of early MF is indistinguishable from that of chronic dermatitis. The limitations of light microscopy in the diagnosis of the CTCLs have led to the development of other diagnostic laboratory techniques. The best approach to the diagnosis of the CTCLs is a multidisciplinary one and should include ultrastructural morphometry, immunophenotyping, immunogenotyping, and histologic evaluation whenever possible. It is the purpose of this overview to point out the strengths and weaknesses of each of these techniques and, together with clinical input, to provide a comprehensive and rational approach to patient care.

Epidermal Langerhans' cell densities influence survival in mycosis fungoides and Sézary syndrome

Because Langerhans' cells (LC) (CD1a-positive epidermal cells) have been discussed to be involved in the pathogenesis of mycosis fungoides and Sézary syndrome, the authors examined the influence of densities of Langerhans' cells and, concurrently, of other phenotypes retrospectively on survival of 35 patients. Cell densities were assessed on cryostat sections (alkaline phosphatase antialkaline phosphatase-technique) of the respective diagnostic biopsy specimens. Additionally, two clinical parameters (age, stage of disease) were evaluated. CD1a-positive epidermal cells were demonstrated to be the only cell population being significantly associated (P = 0.011) with survival. Death resulting from mycosis fungoides and Sézary syndrome was significantly (P = 0.003) less frequent in patients with epidermal CD1a-positive cell densities higher than 90 cells/mm2 (optimal break point) as compared with patients with lower numbers. These results suggest that Langerhans' cells have a significant impact on prognosis of patients with mycosis fungoides and Sézary syndrome. They play an important role in the host defense mechanisms against these lymphomas rather than to favor their progression as proposed recently.