Current understanding of the aetiology and clinical implications of cutaneous graft-versus-host disease

Manifestações tegumentares da doença enxerto contra hospedeiro em pacientes transplantados de medula óssea

A doença enxerto contra hospedeiro (DECH) é uma síndrome sistêmica que ocorre em pacientes que recebem linfócitos imunocompetentes. A fisiopatologia envolve uma reação imunológica entre linfócitos transplantados e tecidos do hospedeiro, e ocorre por ataque imune das células T do doador às células do hospedeiro, as quais diferem daquelas pelos antígenos de histocompatibilidade. É, assim, uma complicação primária do transplante de medula óssea (TMO) alogênico. O envolvimento cutâneo é freqüente na DECH e contribui para a morbidade e mortalidade do TMO. O dermatologista tem papel importante na avaliação dos pacientes auxiliando no reconhecimento precoce da DECH e suas complicações e no acompanhamento clínico desses pacientes. Nesta revisão os autores enfatizam as manifestações cutâneas da DECH, tendo como base sua experiência pessoal no acompanhamento de pacientes portadores de DECH transplantados de medula óssea no Centro Nacional de Transplante de Medula Óssea/Inca/MS, no Rio de Janeiro, nos últimos 14 anos.

Cutaneous manifestations of chronic graft-versus-host disease

Graft-versus-host disease (GVHD) occurs in a number of clinical settings. It is well recognized after bone marrow transplantation, an increasingly used therapeutic option for haematological disorders. Chronic GVHD, occurring at an interval greater than 100 days post-transplant, has many systemic manifestations, but it is the cutaneous manifestations which are most frequent and often most troubling to the patients. In this review article, the wide spectrum of cutaneous chronic GVHD (including involvement of hair, nails and mucosae), and its complications and associations are discussed. The clinical and histological features and management guidelines are presented to assist the dermatologist with diagnosis and treatment of this condition.

Mechanisms of drug eruptions: Part I

The pathogenetic mechanisms underlying common, and less common but severe, adverse cutaneous drug reactions are reviewed. Pharmacogenetic variability may account for a susceptibility to serious drug reactions to sulphonamides and anticonvulsants, as well as to lupus erythematosus (LE)-like syndrome. Exanthematous drug reactions may have an immunological basis. Cell mediated cutaneous drug reactions, including lichenoid reactions, LE-like syndrome, fixed drug eruption, erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis, will inevitably involve elements of the skin immune system. Graft-versus-host disease provides a useful model for aspects of these drug-induced disorders. Urticaria, angioedema, anaphylaxis and anaphylactoid reactions may involve Type I immunoglobulin (Ig)-mediated or Type III hypersensitivity, or may be caused by pharmacological, non-allergic means. Drug-induced vasculitis, serum sickness and the Arthus phenomenon are manifestations of the immune complex disease. Drug-induced pemphigus may involve immune dysregulation, but several thiol-containing drugs are able to cause antibody-independent acantholysis directly.

Immunoelectron microscopy of acute graft versus host disease of the skin after allogeneic bone marrow transplantation

AIMS

To clarify the pathological mechanisms of acute cutaneous graft versus host disease (GvHD) following allogeneic bone marrow transplantation.

METHODS

Skin biopsy specimens from five patients were examined by immunoelectron microscopy. A panel of monoclonal antibodies against T cell and natural killer cell subpopulations was used, including anti-CD4, -CD8, -CD16b, -CD56, -CD57, and -TCR delta 1 antibodies.

RESULTS

All the specimens contained CD8+ cells, CD4+ cells, and CD56+ cells infiltrating the epidermis. Cells stained with anti-CD16b, -CD57, or -TCR delta 1 were very sparse or absent. Most of the CD8+ cells in the epidermis displayed morphological features of activated cytotoxic T lymphocytes and apposition of such cells to degenerating keratinocytes was shown. CD4+ cells outnumbered CD8+ cells in the epidermis in all five cases. Noticeable intercellular as well as intracellular oedema of keratinocytes was observed at the site of prominent CD4+ cell infiltration, suggesting that these also have a role as actual effector cells by secreting cytotoxic cytokines. CD56+ cells infiltrating the epidermis did not exhibit the characteristic ultrastructural morphology of the natural killer cells thus far examined, and their lineage remained uncertain.

CONCLUSIONS

These data provide direct evidence that CD8+ cytotoxic T cells attack keratinocytes, and further suggest that CD4+ cells as well as CD56+ cells participate in the cellular pathogenesis of acute cutaneous GvHD.

Characterization of skin-infiltrating T lymphocytes during acute graft-versus-host disease

A panel of 34 clones was established from a cell line derived from the skin biopsy of a patient (genotype: A1, A2, B7, B8, DR3, DR6) undergoing acute graft-versus-host disease after semiallogeneic bone marrow transplantation with his mother's bone marrow (genotype: A1, A1, B7, B8, DR3, DR6). The T-cell line obtained presented the following phenotype: CD3+, CD4+, CD8-, CD16-, WT31+, T-cell receptor delta 1-, 4B4+, 2H4-, CD25+, DR+. This CD4+ T-cell line was poorly cytotoxic against the target cells tested, including the mother's phytohemagglutinin blasts as a negative control (autologous T cells), the father's phytohemagglutinin blasts bearing the mismatch haplotype, K562, U937, SVK14 (a keratinocyte cell line), and a panel of B-lymphoblastoid cell lines bearing HLA-A2, the known mismatch antigen. All but 1 of the 34 clones obtained were of CD4+ phenotype, and none was CD16+. Only the sole CD8+ clone showed significant cytotoxicity against the father's phytohemagglutinin blast; however, this cytotoxic activity was associated with the highest score for nonspecific killing against both K562 and U937. This work demonstrates the feasibility of obtaining a large panel of clones from a graft-versus-host disease target organ to constitute the basic cellular material for in vitro study of the graft-versus-host process.

Cutaneous manifestations of immunosuppression in organ transplant recipients

Skin disease is a significant cause of morbidity in chronically immunosuppressed patients, including organ transplant recipients. Cutaneous drug reactions may be caused by immunosuppressive therapy that commonly includes corticosteroids, cyclosporine, azathioprine, and antithymocyte and antilymphocyte globulins. Immunosuppressive drugs can also potentiate the effects of other carcinogens, such as ultraviolet radiation, that cause premalignant lesions and squamous cell carcinoma. The risk of Kaposi's sarcoma is increased in these immunosuppressed patients, particularly in renal transplant recipients. Oncogenic viruses such as the Epstein-Barr virus have been associated with the development of non-Hodgkin's lymphoma in transplant recipients. In transplant patients human papillomavirus infections may be predisposed to malignant transformation, particularly at genital sites. Opportunistic infections caused by bacteria, fungi, viruses, or protozoa are the most common cause of death in transplant recipients. Skin manifestations of infection in immunosuppressed patients may be an important clue to their presence.

Interleukin-2 stimulates resting human T lymphocytes' response to allogeneic, gamma interferon-treated keratinocytes

In order to investigate the biologic significance of HLA-DR expression by human keratinocytes, we have examined the possibility that DR-positive keratinocytes become alloantigen presenting cells for resting T cells in the presence of interleukin-2. Using this system, gamma interferon-treated, DR-positive keratinocytes stimulate the proliferation of allogeneic, resting T cells approximately 3-fold whereas non-gamma interferon-treated, DR-negative keratinocytes do not. Because a monoclonal antibody against recombinant gamma interferon inhibits this proliferation, the stimulation is dependent on pre-incubation with gamma interferon. By contrast, since the stimulation is not inhibited by a monoclonal antibody against HLA-DR, it is not clear that the stimulation is due to class II antigen expression by keratinocytes. To rule out that gamma interferon increases the expression of class I antigens, leading to stimulation of resting T cells on that basis, we determined whether gamma interferon treatment enhances class I antigen expression by keratinocytes. The lymphokine treated cells did not demonstrate more class I antigen expression than untreated keratinocytes. Thus, the observed stimulation of allogeneic, resting T cells by gamma interferon-treated keratinocytes in the presence of IL-2 is not due to increased class I antigen expression but is due to other cell surface antigen(s) induced by recombinant gamma interferon treatment. These results suggest that gamma interferon-exposed keratinocytes in the presence of interleukin-2 may augment the activation of resting T lymphocytes and, in this manner, may contribute to cutaneous inflammation.