C-type virus-like particles specifically localized in Langerhans cells and related cells of skin and lymph nodes of patients with mycosis fungoides and Sezary's syndrome. A morphological and biochemical study

Update on Biology of Cutaneous T-Cell Lymphoma

Cutaneous T cell lymphomas (CTCL) comprise of a heterogeneous group of non-Hodgkin lymphomas derived from skin-homing T cells. Variation in clinical presentation and lack of definitive molecular markers make diagnosis especially challenging. The biology of CTCL remains elusive and clear links between genetic aberrations and epigenetic modifications that would result in clonal T cell expansion have not yet been identified. Nevertheless, in recent years, next generation sequencing (NGS) has enabled a much deeper understanding of the genomic landscape of CTCL by uncovering aberrant genetic pathways and epigenetic dysregulations. Additionally, single cell profiling is rapidly advancing our understanding of patients-specific tumor landscape and its interaction with the surrounding microenvironment. These studies have paved the road for future investigations that will explore the functional relevance of genetic alterations in the progression of disease. The ultimate goal of elucidating the pathogenesis of CTCL is to establish effective therapeutic targets with more durable clinical response and treat relapsing and refractory CTCL.

Wasik M, B. Koralov S, Geisler C, Kilian M, Iversen L, Woetmann A, Odum N. Bacterial toxins fuel disease progression in cutaneous T-cell lymphoma

In patients with cutaneous T-cell lymphoma (CTCL) bacterial infections constitute a major clinical problem caused by compromised skin barrier and a progressive immunodeficiency. Indeed, the majority of patients with advanced disease die from infections with bacteria, e.g., Staphylococcus aureus. Bacterial toxins such as staphylococcal enterotoxins (SE) have long been suspected to be involved in the pathogenesis in CTCL. Here, we review links between bacterial infections and CTCL with focus on earlier studies addressing a direct role of SE on malignant T cells and recent data indicating novel indirect mechanisms involving SE- and cytokine-driven cross-talk between malignant- and non-malignant T cells.

Infectious agents in cutaneous T-cell lymphoma

Infectious agents have long been suspected as potential causative agents in cutaneous T-cell lymphoma (CTCL). Tissues of patients with CTCL have been evaluated for evidence of infection with a number of agents, including Staphylococcus aureus, retroviruses, and herpesviruses. These studies have failed to reveal a consistent association of CTCL with investigated agents. However, there is substantial evidence suggesting a potential role of a yet unidentified virus in CTCL. This article will review the findings of studies exploring potential roles of infectious agents in CTCL. In addition, we investigated CTCL tissues for evidence of infection with Merkel cell polyomavirus, a novel polyomavirus that was recently discovered as a probable carcinogenic agent in Merkel cell carcinoma. Cutaneous lesions demonstrating mycosis fungoides were stained with a monoclonal antibody against the Merkel cell polyomavirus T antigen, along with appropriate positive and negative controls. Immunohistochemical stains produced negative results in all examined mycosis fungoides specimens. These findings, which suggest a lack of association of CTCL with Merkel cell polyomavirus, add to the current body of knowledge regarding infectious agents and CTCL.

Human retroviruses in leukaemia and AIDS: reflections on their discovery, biology and epidemiology

The study of retroviruses has had a profound impact by unveiling an unusual form of viral replication: the multiplication of RNA viruses via a proviral DNA, for which Jan Svoboda provided the experimental model over forty years ago. In 1970 Temin, Mizutani and Baltimore discovered that this group of viruses contains a unique enzyme catalysing the synthesis of a DNA copy of the viral RNA: reverse transcriptase (RT). The discovery of RT has itself had an enormous impact on molecular biology in general, but also stimulated many premature claims of its detection in human disease. Claims by Gallo's laboratory that the cytoplasm of human leukaemia cells contained RT proved to be unfounded, as did his report in collaboration with Weiss that myeloid leukaemia contained HL23 virus, this organism proving not to be human but a laboratory contaminant of three monkey viruses. Conclusive demonstration of a retroviral involvement in human leukaemia was first provided in 1981 by Hinuma and his associates, showing that adult T-cell leukaemia (ATL), a rare form of leukaemia endemic to south-west Japan, is caused by a new retrovirus (ATLV). Other publications in December 1980 and through 1981 claimed the discovery of a new human T-cell leukaemia virus involved in mycosis fungoides (MF) and Sézary's syndrome (SS). This virus was termed HTLV by Gallo. The nucleotide sequence of ATLV is strongly conserved, that of my 1983 isolate from a black British ATL patient being practically identical with the Japanese virus isolates. After AIDS was recognised in 1981 by Gottlieb and coworkers as a new human disease, several papers were published by Gallo and his associates during 1983-4, invoking the oncovirus responsible for adult T-cell leukaemia as the cause of AIDS. In 1983 the French scientist Barré-Sinoussi and her colleagues succeeded in isolating a new agent in the disease, a lentivirus, which they named LAV. The French immunologist Klatzmann and his colleagues discovered that LAV killed CD4+ T-cells, furnishing an explanation for the pathogenesis of AIDS and providing a mechanism for how AIDS developed. For some time Gallo continued to suggest leukaemia virus involvement, claiming that his independent isolate of the AIDS virus, termed HTLV-III, was closely related to HTLV-I (the Japanese ATLV). Although this created considerable confusion among researchers for a period, the relationship was eventually disproved. Unlike ATLV, whose nucleic acid sequence is very stable, the AIDS virus (now termed HIV by international agreement) is extraordinarily unstable, the sequences of independent HIV isolates being quite unique: this made it possible to establish conclusively that both HTLV-III and another independent isolate CBL-1, from Weiss' laboratory, were actually LAV isolates from the French laboratory. It has been shown by Hayami and his associates that only African primates are infected with similar lentiviruses to HIV which explains why AIDS started in Africa. Further research has clarified the origin of HIV-1 to be a chimpanzee lentivirus and HIV-2 to be the sooty mangabey lentivirus, which began to spread in humans perhaps no more than fifty years ago. The infection has spread rapidly, primarily through sexual intercourse, but also by transmission through blood and its products as well as contaminated needles and syringes. Sexual intercourse has now spread the virus around the World; and there are probably some 70 million infected. 90% of those infected with HIV develop the deadly disease of AIDS within ten years of infection: the death toll from the disease has been enormous. By contrast, HTLV-1 has been infecting man in isolated areas probably for hundreds of years; but it has not spread widely. HTLV causes leukaemia in only less than 1% of those infected. The prime mode of transmission of HTLV-1 is between mother and neonate; infections can be reduced by stopping breast-feeding by infected mothers. The isolation of HIV enabled screening tests to be developed for contaminated blood. However, due to the peculiar biology of HIV infection, unfortunately all efforts to develop an effective vaccine have so far failed.

In cutaneous T-cell lymphoma, class II MHC molecules on CD1+ antigen-presenting cells are upregulated in involved compared with uninvolved epidermis

CD1+ antigen-presenting cells in involved epidermis of patients with cutaneous T-cell lymphoma exhibit and enhanced functional capacity to activate autologous CD4+ T cells compared with CD1+ antigen-presenting cells from uninvolved and normal epidermis. Class II major histocompatibility complex molecules are involved in antigen presentation, and their expression on CD1+ Langerhans cells is known to vary. The expression of all three class II (HLA-DR, -DQ, -DP) molecules was therefore determined on CD1+ epidermal cells from both involved and uninvolved epidermis, using flow cytometry. The involved CD1+ epidermal cells exhibited a 1.5-1.6-fold, statistically significant increase in fluorescence intensity after staining of the class II molecules (HLA-DR, -DQ, -DP) compared with CD1+ epidermal cells from uninvolved epidermis. The autologous CD4+ T cells, activation was almost completely blocked by anti-HLA-DR, and partly by anti-HLA-DQ and anti-HLA-DP. In contrast, an antibody against class I, and an irrelevant control antibody, had no blocking effect. In a pokeweed mitogen assay it was demonstrated that autologous CD4+ T cells, activated by involved epidermal cells, demonstrated suppressor activity rather than helper activity. The suppressor activity was dependent on the presence of HLA-DR-positive epidermal cells. Thus, in cutaneous T-cell lymphoma, class II molecules on the individual CD1+ antigen-presenting cell are upregulated in clinically involved compared with uninvolved epidermis, and these molecules are crucially involved in activation of CD4+ T cells.

Genotraumatic T cells and cutaneous T-cell lymphoma. A causal relationship?

Mycosis fungoides, or cutaneous T-cell lymphoma (CTCL), is a T-cell mediated chronic inflammatory skin disease, which can occasionally progress with a variable time course to a fatal lymphoma or to a leukaemic form called Sézary's syndrome. Extensive research into CTCL has not yet elucidated the primary pathophysiological mechanisms. Immunohistological studies are so far less helpful than expected in establishing early diagnosis and prognosis of the disease. The proposition that an exogenous virus is the cause of CTCL has not been substantiated. Karyotypic analysis of lymphocytes from the skin and blood of patients with CTCL have shown the existence of several genetically aberrant T-cell clones in the same patient. These changes are discussed as potential primary events for the development of CTCL. The hypothesis is put forward that the development of genotraumatic T lymphocytes is involved in the progression of the disease.

Ultrastructural studies in Langerhans cell histiocytosis: a search for evidence of viral etiology

The ultrastructure of lesional cells in biopsy material from 50 cases of Langerhans cell histiocytosis (LCH) was studied for the effects of virus and/or cytokines. Viral "footprints," which actually represent ultrastructural signs of the effects of cytokines on cells, were found in 76% of the cases. These were detected in lesional Langerhans cells, endothelial cells, and lymphocytes and consisted of tubuloreticular structures, cylindrical confronting cisternae, and curvilinear membranous formations. No virus particles or virus-specific cell products were found. These studies suggest that LCH cells are subject to cytokine stimulation but provide no evidence to implicate a virus in the disease process.

Antibodies against retroviral core proteins in relation to disease outcome in patients with mycosis fungoides

We have studied the relationship of antibodies reacting with human retroviral core proteins to the disease outcome in Finnish mycosis fungoides (MF) patients in a prospective manner. Antibodies recognizing human T-cell leukaemia/lymphoma virus I (HTLV-I) or human immunodeficiency virus type 1 (HIV-1) core proteins were found in 12 of 14 MF patients as shown by the Western blot method. The antibody reactivities showed three patterns: three patients had antibodies cross-reacting with the gag-encoded core proteins of both HTLV-I and HIV-1; seven patients showed antibodies reacting with HTLV-I core proteins only; and the sera of two patients reacted with HIV p24 core protein only. When following the clinical course of these patients, we found that the three patients with antibodies cross-reacting with both viruses had the most fulminant clinical course, and the overall duration of MF was, on average, 4 years less than in the rest of the patients. None of the patients, however, became leukaemic, or showed any other features suggestive of acute T-cell leukaemia/lymphoma (ATL). Two patients, who did not show anti-retroviral antibodies during the follow-up, had a stable disease with plaque-type skin lesions. Histological or immunohistological typing of the skin infiltrates did not correlate with the disease outcome or the above antibody patterns. Our results thus raise the possibility that an unknown retrovirus, immunologically related to the known human retroviruses, may be aetiologically linked to MF.

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.

Langerhans cells and mycosis fungoides--a critical overview of their pathogenic role in the disease

Skin biopsies from seven patients with mycosis fungoides in various clinical stages (patches, plaques, nodules) were studied immunohistochemically and ultrastructurally, with the aim of investigating and quantifying the distribution of Langerhans cells and their relationships to mycosis cells. Our findings have revealed that in patches and plaques both Langerhans cells and mycosis cells were numerous in the epidermis. Notwithstanding this, in all the specimens examined, only one Langerhans cell forming close contact with a mycosis cell was detected. In the nodules, Langerhans cells and mycosis cells were sparse in the epidermis and no contacts were seen between them. Moreover, in all the patients studied, only a single Langerhans cell was found in the dermal infiltrate without any closely related mycosis cells. Conversely, numerous interdigitating cells have been found in the dermis of patches and plaques, often tightly adhering to mycosis cells. In the nodule, a few scattered interdigitating cells were seen, but often these had close contacts with neoplastic lymphoid cells. These findings indicate that close apposition between Langerhans cells and mycosis cells, which led previous authors to hypothesize a persistent stimulatory action of Langerhans cells on T lymphocytes, eventually leading to the malignant transformation of the latter, is unusual in mycosis fungoides. Therefore, if such a pathogenic role may be attributed to accessory cells in mycosis fungoides it is more probably exerted by dermal interdigitating cells and not by Langerhans cells, as previously proposed.

Interdigitating reticulum cells in dermatopathic lymphadenitis: freeze-fracture and ultrathin-section morphology

Dermatopathic lymphadenitis is a non-neoplastic lesion found with various chronic skin lesions and associated with hyperplasia of the thymus-dependent (T) areas. These areas consist chiefly of interdigitating reticulum cells (IDC's), which are known to be accessory cells for T-cell-dependent immune reactions. The most characteristic features of IDC's are the bizarre-shaped cell nucleus, numerous cytoplasmic processes, deep cytoplasmic invaginations, and a close topographical relationship to surrounding (T) lymphocytes. The cytoplasmic processes of IDC's do not interdigitate with adjacent lymphocytes, as previously reported in the literature, but show close interdigitations with the processes of neighboring IDC's. With the freeze-fracture technique it can be seen that IDC's exhibit a characteristic distribution of intramembranous particles (IMP). While, for example, macrophages, epithelioid cells and lymphocytes display a clearly greater number of IMP on the P face than on the E face, IDC's show an equally high particle density on both the P face and the E face. The organelle content of IDC's in dermatopathic lymphadenitis varies considerably. Tubular profiles, the Golgi apparatus and vesicles may be increased in number. Birbeck granules are also found in IDC's, but only rarely. Variations in the numbers of the different cytoplasmic organelles may be a reflection of varying degrees of metabolic activity of IDC's.

Topical mechlorethamine therapy for early stage mycosis fungoides

One hundred seventeen patients with mycosis fungoides were treated with topical mechlorethamine hydrochloride. The probability of achieving a clinically apparent remission within 2 years of therapy was 75.8% in patients with stage I disease, 44.6% in patients with stage II disease, and 48.6% in patients with stage III disease. Patients with stage I disease achieved complete remission sooner (median, 6.5 months) than patients with stage II (median, 41.1 months) or stage III (median, 39.1 months) disease. The median time to relapse was 44.5 months. Sixty-eight patients (58.1%) developed a delayed hypersensitivity reaction, but only one patient had to discontinue therapy as a consequence. No appreciable differences were seen in the probability to achieve complete remission or time to complete remission as stratified by gender, substage, or the development of a delayed hypersensitivity reaction. Survival analysis revealed that the probability of surviving at 5 years was 89% for all patients. These findings compare favorably with results with other treatments for early stage mycosis fungoides.

C-type particles are inducible in Se-Ax, a continuous T-cell line from a patient with Sézary's syndrome

Se-Ax is a continuous mature T-cell line that we have established from a patient with Sézary's syndrome. An important finding was that the Se-Ax cell line required human serum for initial growth. Here we show that transfer of the permanent cell line to a medium deficient of human serum induces production of C-type retroviral-like particles with a unique morphology. Ultrastructurally, these particles are 120 nm in diameter with hexagonal shape, and show a small, centrally located round core of 30 nm. They are observed only extra-cellularly; typical budding, however, is not found. Both by serological testing and molecular analysis we substantiate the morphological conclusion that these particles do not represent common human or animal retroviruses. The inducibility of the particles may be a hint as to a possible endogenous origin.

Treatment of mycosis fungoides with recombinant interferon-alpha 2a2 alone and in combination with etretinate

Eleven patients with mycosis fungoides (MF) were treated with recombinant alpha-interferon (rIFN-alpha 2a2) in combination with etretinate (seven patients) or alone. One patient, who also received etretinate, went into complete remission and remained without signs of MF after 18 months. Six patients experienced partial remission; one of these was treated with rIFN-alpha 2a alone and was clinically in complete remission, but had still a pleomorphic skin infiltrate. Two patients were non-evaluable, and two stopped therapy due to progressive disease. Five patients discontinued therapy due to side-effects although three had partial remission of their disease. Only four patients received 12 months therapy. The study shows that rIFN-alpha 2a in combination with etretinate or alone can induce remission of MF.

Role of epidermal Langerhans cells in viral infections

Langerhans cells function as highly potent antigen-presenting cells in the epidermis. In the last few years, their role in viral infections has been studied in various experimental systems. They have been shown to be involved in the pathogenesis of a number of infections of viral origin. These include vaccinia virus, human papilloma virus, herpes simplex virus, foot and mouth disease virus and human retrovirus infections. Studies on the effect of various factors, that are known to modulate the activity and density of Langerhans cell in the epidermis, may lead in the future to the development of new strategies aimed at inhibiting virus infections or even eradicating latent infection.

Interdigitating reticulum cells in lymph nodes of Sézary syndrome. Freeze-fracture and ultrathin-section morphology

Lymph nodes with extensive leukemic infiltration from three patients with the Sézary syndrome were examined in ultrathin sections and in freeze-fracture replicas. Sézary cells (SC) and interdigitating reticulum cells (IDC) were the predominant cell types in the lymph nodes. Both were closely connected with each other by apparently interdigitating cytoplasmic processes. The projections between these cells were, in the main, processes from the IDC. In freeze-fracture replicas these cellular processes did not appear as interdigitations but were more bubble-like, and for this reason these cells are imprecisely described by the term "interdigitating." The SC were seen to possess only short cytoplasmic processes. The frequent polar grouping of cell organelles in SC in the region of the contact zone with IDC and the high organelle content of IDC ('activated IDC') could be the morphologic expression of intense interaction between IDC and SC. IDC displayed three features in freeze-fracture which are not specific to the Sézary syndrome, but should be applicable to IDC in general: (1) they exhibited an approximately equal density of intramembrane particles in both the E-face and the P-face, (2) some of the intramembrane particles in the P-face were assembled in clusters and (3) the surface showed bubble-like formations of the cytoplasmic processes. On the basis of these properties it was possible to distinguish IDC from macrophages and lymphocytes in freeze-fracture replicas.

Studies of human retroviruses in relation to adult T-cell leukaemia, acquired immune deficiency syndrome, and multiple sclerosis

Studies of adult T-cell leukaemia virus/human T-cell leukaemia/lymphotropic viruses (ATLV/HTLV-I) in Japan indicate that the virus is involved only with the development of ATL. By contrast, reports from the U.S.A. about HTLV have from time to time claimed that related HTLV are concerned not only with ATL of black persons, but also with a wide range of diseases, such as mycosis fungoides/Sezary's syndrome, T-cell hairy cell leukaemia, acquired immune deficiency syndrome (AIDS) and also multiple sclerosis. Using morphological, biological, serological and molecular hybridisation studies, we were able to confirm that the viruses implicated in the development of ATL and AIDS are distinct and that ATLV/HTLV-I is involved only in ATL, and HIV/LAV/HTLV-III only in AIDS. In vitro, ATLV/HTLV-I transformed and immortalised T-cells, while HIV/LAV/HTLV-III killed our T-cells. Failure to detect any serological cross-reaction indicates that all the structural proteins are different. Likewise, Southern blot studies failed to reveal any cross-hybridisation. Sixty patients with multiple sclerosis failed to reveal any association with ATLV/HTLV-I or with HIV/LAV/HTLV-III. Our conclusion is that ATLV/HTLV-I is involved only in ATL of Japanese and of some black persons of African origin, and that HIV/LAV/HTLV-III is associated only in AIDS.

A continuous T-cell line from a patient with Sézary syndrome

A continuous cell line, Se-Ax, from a patient with Sézary syndrome has been established. The Se-Ax cell line is IL-2 dependent, requires human serum for permanent growth, and has the following phenotype: CD1-, CD2+, CD3+, CD4-, CD5-, CD8-, CD20-, CD25+; it expresses the T9, T10, and HLA-DR antigens. This cell line reveals multiple chromosome aberrations as seen in the most abundant abnormal clone in peripheral blood. Therefore, it is not unlikely that it derives from tumor cells. A putative cytotoxic cell line derived from the same patient has only weak killer-cell activity against the autologous permanent cell line: this CD8+ cytotoxic cell line has a 14q+ chromosomal marker. The fact that the patient demonstrated no natural killer-cell or activated killer-cell activity against the Se-Ax cell line may in part explain the successful establishment of the continuous cell line from bulk culture.

Does radiation-induced abrogation of skin Langerhans cell functions lead to enhanced incidence of skin tumors in patients with genetic disorders of DNA repair?

A hypothesis is presented which states that persons with the genetic disorders xeroderma pigmentosum and ataxia-telangiectasia, manifested by a deficiency of DNA repair, develop cutaneous tumors due to the elimination of reticuloendothelial system cells (Langerhans cells) in the skin, and the subsequent loss of control of epidermal cellular elements.

Abatement of Sézary syndrome lesions following treatment with acyclovir

Sézary syndrome is a malignant form of cutaneous T cell lymphoma in which patients characteristically present with generalized pruritic erythroderma and large numbers of circulating Sézary cells in the peripheral blood. Several previous studies have proposed that viruses may play a role in the cause of cutaneous T cell lymphoma. This report describes a 68-year-old man with Sézary syndrome who received a seven-day course of intravenous acyclovir for treatment of disseminated herpes zoster and was noted to have almost complete disappearance of generalized erythroderma and pruritus. Since acyclovir has been shown to selectively inhibit viral DNA polymerase, the observed clinical response is strong evidence that viruses play a role in the cause of cutaneous T cell lymphoma. Mechanisms that could explain the observed response are discussed, and further studies on the utility of antiviral agents for treatment of cutaneous T cell lymphoma and on possible inhibitory effects of acyclovir on retroviruses are recommended.

Dendritic cells in the dermal infiltrate of Sézary syndrome

The dermal infiltrates of four patients with the Sézary syndrome were studied by electron microscopy and the data were evaluated quantitatively. The nuclear contour index of lymphocytes was calculated, and many tumour cells had an index greater than 6.5. Dendritic cells were found in all cases. The dendritic cells contained smooth and rough endoplasmic reticulum, moderately well-developed Golgi apparatus, scanty lysosomes and many thin and intermediate filaments; their surface was scalloped with numerous vesicles. Birbeck granules were not found in the cytoplasm of dendritic cells. Dendritic cells comprised 24% of infiltrating cells and were interspersed with lymphocytes; 75% of the lymphocytes were in contact with dendritic cells; 35% of the lymphocytes in contact with dendritic cells had a nuclear contour index higher than 6.5 and 76% had a nuclear contour index higher than 5. The data strongly suggest a functional relationship between lymphocytes and dendritic cells in the dermal infiltrate of Sézary syndrome. They are discussed in relation to the hypothesis that the disease is a consequence of chronic immune stimulation.

Acute glandular fever-like illness in a patient with HTLV-III antibody

A lymph node biopsy obtained from a patient with human T-cell lymphocytotropic virus III/lymphadenopathy-associated virus (HTLV-III/LAV) antibody, presenting with an acute glandular fever-like illness, was examined by electron microscopy. Numerous pathological changes were present in the biopsy, including hypertrophy of smooth endoplasmic reticulum, intracytoplasmic rod-like inclusions within the cisternae of endoplasmic reticulum, multivesicular bodies, test-tube and ring-shaped forms, and tubulo-reticular structures. Intranuclear and intracytoplasmic viral-like particles measuring 105-120 nm in diameter and small cytoplasmic particles measuring 50-70 nm in diameter were found in some degenerating lymph node cells. These pathological findings may reflect a host cell response to various pathological and viral stimuli resulting from immune deficiency owing to infection with HTLV-III/LAV.

The lymph node in mycosis fungoides: a light and electron microscopy and immunohistological study supporting the Langerhans' cell-retrovirus hypothesis

This paper describes the light and electron microscopy and monoclonal antibody findings in the lymph nodes of nine patients with mycosis fungoides. Four cases showed dermatopathic change characterized by close association between small convoluted T4 lymphocytes and T6 antigen-presenting cells (Langerhans' and indeterminate dendritic cells) in the sinuses and paracortical zones. The T4:T8 ratio was between 3 and 5:1. One case showed dermatopathic change but included large convoluted T4 lymphocytes and occasional T10 lymphocytes. The T4:T8 ratio was 4:1. The antigen-presenting cells were mostly T6 negative (interdigitating reticulum cells). One case showed extensive paracortical expansion by small and large convoluted T4 lymphocytes. The T4:T8 ratio was 20:1. Few B lymphocytes and antigen-presenting cells were present. Two cases showed partial and one case total effacement by atypical lymphoid tissue. This included small and large convoluted T4 lymphocytes and T4 immunoblasts. The T4:T8 ratios were between 30 and 40:1. The changes in their antigen-presenting cell population were complex. Langerhans' cells in one case generally failed to express T6 antigen and in two displayed histiocyte features. In one case, both immature and budding type C retrovirus-like particles were identified in Langerhans cells. One extracellular mature type C virus-like particle was identified in another case. No ultrastructural distinction could be made between similarly sized primary lysosomes and possible intracytoplasmic mature type C retrovirus particles. These findings support the hypothesis that mycosis fungoides may represent an altered dermatonodal cycle resulting from an interaction between retrovirus, Langerhans' cells and lymphocytes.

Monoclonal antibodies and cutaneous T cell lymphoma. Theoretical and practical considerations

The T cell nature of mycosis fungoides and Sézary syndrome was established a decade ago. The recent advent of monoclonal antibodies to T cells and other lymphoid subpopulations has resulted in an explosion of knowledge on the biology of this group of disorders. These reagents have increased our knowledge on thymic differentiation status, pathogenesis, the phenotype of premalignant vs malignant lymphocytic infiltrates, the identification of other previously unrecognized cells within lymphomas, and the phenotype of circulating vs skin lymphocytes. Therapeutic applications may result. These new developments are discussed.

Establishment of T and B cell lines from patients with mycosis fungoides

Eighteen patients with mycosis fungoides were studied in order to establish cell lines that might be associated with the human T cell leukaemia-lymphoma virus (HTLV). Three T cell lines were established, two from affected skin and one from a lymph node showing dermatopathic lymphadenopathy. The T cells expressed OKT3 and OKT4 antigens. They temporarily expressed an HTLV p19-like antigen in up to 5% of the cells during culture. None of our patients had lymphocytosis or abnormal lymphocytes, except one patient with Sézary's syndrome. We could not establish T cell lines from peripheral blood, but five B lymphoblastoid cell lines were obtained, all positive for the Epstein-Barr virus nuclear antigen. Our finding that T cell lines can be established from skin biopsies and lymph nodes of patients with mycosis fungoides, but not from the blood, supports the concept of a malignant T lymphocyte primarily localized in the skin. The temporary expression of HTLV p19 antigen may indicate the presence of retrovirus, but further studies are needed.

Caribbean T-cell lymphoma/leukemia

Caribbean T-cell lymphoma/leukemia (CATL) is a recently described neoplasm similar to Japanese adult T-cell leukemia/lymphoma, but it occurs in patients born in a different geographic region. Four adult Black West Indian women with CATL were studied using a multiparameter approach, including clinical, hematologic, pathologic, and immunologic investigations. The disease was usually characterized by adenopathy (with or without hepatosplenomegaly), peripheral blood involvement, hypercalcemia often in the absence of gross bony lesions, and a poor prognosis. The neoplastic cells were pleomorphic with marked nuclear irregularity of a multilobated or more cerebriform type. Lymph node biopsies demonstrated a diffuse pleomorphic lymphoma with variable degrees of nuclear irregularity and transformation. Marrow involvement consisted of focal nodules or, more commonly, scattered atypical lymphoid cells. Marrow biopsies also often demonstrated osteoclastic activity. Cases were all of T-cell origin, most commonly of T-helper phenotype, although there was some phenotypic heterogeneity. All patients had antibodies to the human T-lymphoma/leukemia virus.

Increased 2',5'-oligoadenylate synthetase activity in blood mononuclear leukocytes from patients with advanced cutaneous T-cell lymphoma

The activity of the interferon-induced enzyme 2',5'-oligoadenylate synthetase (2',5' An synthetase) was found to be increased in the lysates of peripheral blood mononuclear leukocytes obtained from 10 of 25 (40%) patients with cutaneous T-cell lymphoma (mycosis fungoides and Sézary syndrome). A positive association was found between the level of mean total synthetase activity and extent of involvement (stage) of disease. However, the leukocytes from two patients with relatively high proportions of neoplastic T-cells in the blood (Sézary syndrome) had negligible enzyme activity. It is speculated that increased interferon production in vivo may account for the observed enzyme changes in normal blood leukocytes from these patients, and that the neoplastic T-cell population is the most likely source of the presumed interferon production. Possible mechanisms and biologic consequences of high levels of endogenous interferon in patients with cutaneous T-cell lymphoma are discussed.

Langerhans cells in squamous exocervical carcinoma: a quantitative and ultrastructural study

The gross morphology, density, distribution, and ultrastructure of the Langerhans cell (LC) in the human exocervix in cases of cervical intraepithelial neoplasia (CIN) and incipient carcinoma were investigated. Two zinc-iodide-osmium (ZIO) procedures were applied to epithelial sheets and to tissue sections for light and electron microscopy. The ZIO methods as well as conventional electron microscopy revealed the presence of LCs in CIN, in the invasive prongs, and in the lymphoid infiltrate of the chorion. The epithelial sheets demonstrated a LC density 3.5 times higher than we have previously reported for the normal exocervix. The region around the external os displayed the highest LC density and the most advanced grades of CIN. The LCs were classified into six types according to the number of processes and secondary branches. The most ramified types were more abundant in the neoplastic exocervix than in the normal exocervix. The LC in all locations of the exocervix with carcinoma showed hypertrophy of the rough and smooth endoplasmic reticula and a large number of filaments. The RER displayed dilated cisternae containing electron-dense material. Specialized contacts between LCs and lymphocytes were an outstanding finding. These findings suggest that the LC might play an important role in the neoplastic process.

Tumor viruses, oncogenes, and human cancer

We review the biology of transforming retroviruses and their relationship to cellular transforming genes (tumor oncogenes). Evidence is discussed for the involvement of a retrovirus in a newly described syndrome, "adult T cell leukemia/lymphoma," which has a high incidence of skin involvement. This virus is related to the animal retroviruses which induce tumors in susceptible hosts after a long latent period. Cellular transforming genes encode proteins which directly change the oncogenic potential of a cell. These genes, which are altered forms of normal cellular genes, have been isolated from a wide variety of human tumors. Viral and cellular transforming genes produce their changes by at least two different mechanisms: abnormally high production of the normal protein encoded by these genes, or normal levels of an altered form of the protein.