The immunopathogenesis of cutaneous T-cell lymphoma. Abnormal cytokine production by Sézary T cells.
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Animals↗
Biomedical subjects
B R Vowels
Publications and source records attributed to B R Vowels.
Therapeutic applications of photopheresis.
Photopheresis is a useful therapy for advanced cutaneous T-cell lymphoma, particularly for Sezary syndrome. Additional conditions in which clinical studies have suggested a therapeutic role for photopheresis include certain autoimmune diseases and reversal of rejection of solid organ allografts. Because photopheresis is extremely well tolerated and evidence is lacking for a direct immunosuppressive effect produced by this therapy, randomized trials should be pursued to determine the full spectrum of clinical benefit of this novel therapeutic modality.
Autoimmune Diseases↗
Extracorporeal photochemotherapy induces the production of tumor necrosis factor-alpha by monocytes: implications for the treatment of cutaneous T-cell lymphoma and systemic sclerosis.
Extracorporeal photopheresis (ExP) has been shown to be an efficacious and well-tolerated therapy in the treatment of cutaneous T-cell lymphoma (CTCL) and systemic sclerosis. However, the precise mechanisms of its action have not been defined. Because of a correlation between the development of fever in the early phase of treatment of CTCL and subsequent anti-tumor responses, we examined the production of the proinflammatory, pyrogenic cytokines tumor necrosis factor-alpha (TNF), IL-6, IL-1 alpha, and IL-1 beta before and after ExP. Monocytes were purified from peripheral blood specimens of normal volunteers (n = 4) or from peripheral blood specimens of CTCL (n = 6) or systemic sclerosis (n = 3) patients that were obtained immediately prior to ExP and also directly from the photopheresis unit after ExP, just prior to reinfusion into the patient. Monocytes were then cultured under various conditions for 16 h, after which the culture supernatants were collected and assayed for specific cytokine production. ExP induced a significant increase in the production of TNF (p less than 0.008) and IL-6 (p less than 0.05) as compared to non-ExP-treated cells, whereas no significant differences were observed in IL-1 alpha (p less than 0.5) and IL-1 beta (p less than 0.2) production following ExP. Exposure of monocyte cultures to IFN-gamma (100 U/mL) either before or after ExP further enhanced TNF production by 4 to 28 times. In contrast, incubation with IFN-alpha (100 U/mL) had no significant effect on TNF production. Addition of TNF (500 U/ml) to monocyte cultures obtained prior to ExP resulted in a slight but insignificant increase in TNF production in 2 of 10 cases. However, when monocytes obtained prior to ExP were incubated with 8-methoxypsoralen (8-MOP, 100 ng/ml), exposed to ultraviolet light A (UVA, 2J/cm2), washed, and then incubated with TNF, a significant increase (p less than 0.01) in TNF production was observed in 8 of 10 cases, suggesting that the combination of 8-MOP and UVA may sensitize cells to TNF. Based on studies of endotoxin (LPS)-stimulated production of TNF by monocytes, levels of endotoxin in culture reagents or photopheresis equipment could not account for the increased production of TNF following treatment by ExP. Increased TNF production as a result of ExP may have important implications for treating both CTCL and systemic sclerosis because, in the case of CTCL, it could mediate numerous anti-tumor effects, whereas, in the case of systemic sclerosis, it could suppress collagen synthesis and induce collagenase production.
Endotoxins↗
Aberrant cytokine production by Sezary syndrome patients: cytokine secretion pattern resembles murine Th2 cells.
Sezary syndrome (SzS), the leukemic stage of cutaneous T-cell lymphoma (CTCL), is typically a CD4+ T-cell lympho-proliferative disease characterized by numerous immunologic abnormalities, including decreased T-cell responses to antigens and mitogens, decreased natural killer and lymphocyte-activated killer cell activities, eosinophilia, and increased levels of immunoglobulins, particularly IgE and IgA. Because this constellation of abnormalities is reminiscent of the pleiotropic in vitro activities of IL-4 and IL-5, we examined the possibility that malignant T cells in SzS may be producing increased amounts of IL-4 with a concomitant decrease in IL-2 and IFN-gamma production. Such a cytokine secretion pattern would be similar to that produced by murine Th2 cells. Serum IL-4 enzyme-linked immunosorbent assay measurements revealed that 33% of SzS patients (n = 21) had levels of IL-4 significantly higher (mean, 7.2 pg/ml; range, 0-48, p less than 0.05) than normal controls (mean, 1.59; range, 0-3.1). Although the majority of tested patients had elevated serum IgE, no direct correlation between serum IL-4 levels and serum IgE levels was observed. Peripheral blood mononuclear cells (PBMC) isolated from SzS patients and stimulated with phytohemagglutinin (PHA) produced significantly higher levels of interleukin (IL)-4 and significantly lower levels of IL-2 and interferon (IFN)-gamma than did PBMC from normal controls (p less than 0.02, p less than 0.05, and p less than 0.02, respectively). PBMC from SzS patients in remission produced IL-4 and IL-2 levels similar to that of the normal controls. To determine if IFN-gamma could inhibit the increased IL-4 production by PHA-stimulated PBMC from SzS patients, IFN-gamma was added to culture at 0, 24, or 48 h prior to the addition of PHA. Significant decreases in IL-4 production were seen only in cultures incubated with IFN-gamma for 24 and 48 h prior to the addition of PHA. IL-2 levels were not affected by IFN-gamma incubation. The increased IL-4 and decreased IL-2 and IFN-gamma production by PBMC from SzS patients suggests that Sezary cells have a cytokine profile similar to murine Th2 cells. Moreover, this cytokine secretion pattern may play an integral role in the immunopathogenesis of advanced CTCL. The results also suggest that IFN-gamma be a useful component in the spectrum of therapeutic approaches to SzS.
Animals↗
Natural killer cell activity of rhesus macaques against retrovirus-pulsed CD4+ target cells.
Rhesus peripheral blood mononuclear cells (PBMC) fail to demonstrate natural killer (NK) activity against the human T-cell lines CEM, CEM x 174, or SUP-T1. However, these cell lines could act as NK-sensitive target cells if they were pulsed with heat-inactivated, whole simian immunodeficiency virus (SIV). The ability of these SIV-pulsed T-cell lines to act as NK-sensitive target cells was directly related to the relative density of CD4 on their surface. Target cell generation was inhibited by preincubation of cell lines with CD4 monoclonal antibody (MAb) with specificity for the SIV binding site. In addition, NK activity was seen against target cells that had been prepared with human immunodeficiency virus type 1 (HIV-1) gp120, nonglycosylated gp120, env A of feline leukemia virus (FeLV), and simian type D retrovirus (SRV). Addition of leupeptin to target cells prior to SIV pulsing did not result in a significant decrease in cytotoxic activity, suggesting that processing is not required for the generation of target cells. The cells that mediate NK activity are nonadherent, do not form rosettes with AET-treated sheep red blood cells (SRBC), and are phenotypically CD16+ and CD8+. NK activity of SIV-infected macaques was significantly decreased against both K562 cells and SIV-pulsed target cells as compared with uninfected animals. However, treatment of PBMC with interleukin-2 (IL-2) resulted in a partial restoration of NK activity.
Animals↗
Simian immunodeficiency virus-specific T-cell-mediated proliferative response of infected rhesus macaques.
While cell-mediated immunity is known to play an important role in controlling viral infections, its role in human and experimental animal models of human AIDS has not been established. To address this issue, four juvenile rhesus macaques were infected with simian immunodeficiency virus SIVMAC. Freshly isolated peripheral blood mononuclear cells from these SIVMAC-infected macaques and four uninfected control macaques were assessed for T-cell proliferative activity to SIV, monthly, for 10 consecutive months. T cells from SIV-infected monkeys failed to proliferate in response to SIV added directly to the culture. However, when SIV was processed by autologous antigen-presenting cells prior to culture with purified T cells, proliferative responses were uniformly demonstrated in SIV-infected monkeys, but not in uninfected controls. Proliferation in response to heat-inactivated SIV was mediated by CD4+ T cells and was shown to be MHC class II-restricted. However, the proliferative response to infectious SIV was mediated by both CD4+ and CD8+ T cells and was MHC class-restricted. As disease progressed, a decline in the T-cell proliferative response was observed.
Animals↗
Cellular immune response of SIV-infected rhesus macaques.
Optimal conditions for the assessment of T cell proliferation and cytolytic T lymphocyte (CTL) responses specific for primate lentivirus were established. CTL and T cell proliferative responses were demonstrated as early as two weeks post-infection. Although the majority of CTL were CD8+, MHC class I-restricted, this study demonstrated CD4+, MHC class II-restricted CTL. Experiments also demonstrated that CTL were CD16 negative. Target cell generation could be blocked with CD4 mAb specific for the SIV binding site.
Animals↗
Characterization of simian immunodeficiency virus-specific T-cell-mediated cytotoxic response of infected rhesus macaques.
Four juvenile rhesus macaques were infected with simian immunodeficiency virus (SIV)MAC-Freshly isolated peripheral blood mononuclear cells (PBMC) from these SIVMAC-infected and from uninfected control macaques were assessed for cytotoxic T-lymphocyte (CTL) activity monthly for 7 consecutive months, beginning 2 months after infection. Target cells consisted of major histocompatibility complex (MHC) haploidentical parental PBMC which were stimulated with mitogen and then pulsed with heat-killed SIVMAC. CTL activity was demonstrated on all four infected animals. The effector cells are T cells which mediate cytotoxicity against SIVMAC-pulsed target cells in an MHC-restricted manner. Furthermore, the cytotoxicity is virus specific and predominantly, if not exclusively, mediated by CD8+ T cells; it is also MHC class-I restricted. Incubation of target cells with leupeptin prior to the cytotoxic assay inhibited target cell generation, suggesting that viral antigens are processed via an endocytic pathway.
Animals↗
S. aureus isolation from the lesions, the hands, and the anterior nares of patients with atopic dermatitis.
Staphylococcus aureus colonization is common in atopic dermatitis (AD) and can exacerbate the disease. Additionally, some evidence shows that patients with AD may act as reservoirs for S. aureus transmission to others. This study compared S. aureus colonization in AD patients and their caregivers with control patients and their caregivers. Quantitative cultures were obtained from the lesions, clinically normal skin, hands, and anterior nares of 100 patients with AD, 100 controls with other cutaneous disorders, and 200 caregivers. AD patients had a significantly greater carriage of S. aureus from lesional and clinically normal skin as well as the hand. Significant increases in carriage of S. aureus were found in the anterior nares and hands of caregivers of AD patients compared with control caregivers. Topical corticosteroid use did not affect recovery of S. aureus. There was a significant correlation between recovery of S. aureus from lesional skin and recovery from the anterior nares (p = .002) and hands (p < .0001). These findings suggest that the anterior nares and the hands may be important reservoirs and vectors for transmission of S. aureus to lesional skin and to close contacts of these patients.
Adolescent↗