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Upregulation of MHC Class I Molecules on Human Dermal Microvascular Endothelial Cells by Interferon α
Microvascular Research 62, 204 –207 (2001) doi:10.1006/mvre.2001.2319, available online at http://www.idealibrary.com on
BRIEF COMMUNICATION Upregulation of MHC Class I Molecules on Human Dermal Microvascular Endothelial Cells by Interferon ␣ Van Anh Nguyen, 1 Christina Fu¨rhapter, and Norbert Sepp Department of Dermatology, University of Innsbruck, A-6020 Innsbruck, Austria Received January 29, 2001; published online June 20, 2001
INTRODUCTION Endothelial cells (EC) play a critical role in the induction and modulation of immunologic and nonimmunologic inflammatory processes. As the lining cells of the vasculature, EC are constantly exposed to circulating blood-borne immune effector cells serving as regulators of leukocyte traffic from the intravascular spaces into tissue parenchyma through distinct adherence proteins on the surface of both leukocytes and endothelium [8]. There are significant data demonstrating that proinflammatory cytokines are able to alter the expression of these proteins on EC and, as a result, facilitate their participation in immune responses [9]. It is well recognized that MHC antigens on cells govern the interaction with T-lymphocytes and are involved in the activation of these immune cells [2]. Several authors have reported that, under standard culture conditions, human EC constitutively express class I MHC, but not class II MHC, molecules [7]. 1 To whom correspondence and reprint requests should be addressed at the Department of Dermatology, University of Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria. Fax: 0043/512-504-3017. E-mail: [email protected].
204
In vitro studies examining the expression and regulation of MHC proteins on endothelium were performed predominantly on EC derived from large-vessel human umbilical veins (HUVEC). It is noteworthy that recent studies revealed distinct differences between large-vessel and microvascular EC in regard to cell surface phenotype and cytokine responsiveness [13]. Herein, we have investigated the influence of IFN␣ on the expression of class I MHC antigens on the surface of human dermal microvascular EC (HDMEC) cultured in vitro, using indirect immunofluorescence and FACS quantitation.
MATERIALS AND METHODS Isolation and culture of HDMEC. HDMEC were isolated from surgically removed normal foreskins obtained from newborns and children up to 7 years old according to a modification of a previously described technique [11]. Culture of EC line HMEC-1. The HMEC-1 line was a generous gift from E. W. Ades and propagated as previously described in detail [1]. 0026-2862/01 $35.00 Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.
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FIG. 1. Dose response. Upregulation of class I MHC expression on HDMEC (upper row) and HMEC-1 (lower row) by INF␣ as determined by fluorescence flow cytometry. Cells were stimulated for 48 h with 10 (a), 100 (b), and 1000 U/ml (c). (. . .) Isotype control Ig2a without addition of IFN␣, (䡠 䡠 䡠) cells stained with MoAb W6/32 without addition of IFN␣, (- - -) isotype control Ig2a with addition of IFN␣, (—) cells stained with MoAb W6/32 with addition of IFN␣.
Antibodies and cytokines. Hybridomas producing monoclonal antibody (MoAb) W6/32, which recognizes MHC class I molecules, was obtained from the American Type Cell Culture (Rockville, MD). AntiHLA-DR antibody was a gift from Becton–Dickinson (San Jose, CA). MoAb JC 70A and MoAb EN4, which both identify CD31 antigen, were provided by Dako A/S (Glostrup, Denmark) and Harlan Sera-Lab Ltd. (England), respectively. IFN␣ 2a was a gift from Schering Plough Corp. (U.S.A.). IFN␥ and TNF␣ were kindly donated by Dr. G. R. Adolf (Bender & Co., Vienna). FITC-conjugated sheep anti-mouse IgG (Fab)⬘ was obtained from Dako A/S. Cytokine stimulation and fluorescent staining of HDMEC and HMEC-1. HDMEC and HMEC-1 were stimulated with various concentrations of cytokines (10, 100, and 1000 U/ml). Control cultures had only the addition of fresh media. After incubation at 37°C for varying times (4, 24, 48, and 72 h), the cells were exposed to 0.05% trypsin/0.5 mM EDTA (Sigma Chemicals) for 5 min to produce a monodispersed suspension. The harvested cells were washed in PBS with 0.5% BSA (Boehringer Ingelheim, Germany), counted, and aliquoted at 100,000 cells/tube for antibody staining. Unconjugated MoAb were incubated on ice for 30 min with cells. The cells were washed in PBS with 0.5% BSA and counterstained with fluores-
ceinated sheep anti-mouse IgG. After an additional 30 min incubation, the cells were washed as above and resuspended in PBS with 0.5% BSA. Flow-cytometric analysis of HDMEC and HMEC-1. Expression of various EC surface markers was quantitated by flow cytometry using a FACS analyzer (Becton–Dickinson) as described elsewhere [11].
RESULTS Influence of IFN␣ on HDMEC and HMEC-1 expression of class I and class II MHC molecules. Incubation of HDMEC with IFN␣ led to a dose- and timedependent increase of class I MHC expression. Doses as low as 10 U/ml induced a slight upregulation, but maximal expression of class I MHC antigens required doses up to 100 U/ml (Fig. 1). No increase in MHC class I was noted at any dose point at 4 h. Elevation of surface expression started to be evident after 24 h exposure to IFN␣ and was most prominent after 48 h at a dose level of 1000 U/ml (Fig. 2). Treatment of HMEC-1 with IFN␣ resulted in a similar time and dose response, with maximal class I MHC expression being seen after 48 h stimulation under doses up to 100 U/ml (Figs. 1 and 2). In vitro incubation of both
Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.
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FIG. 2. Time course. Upregulation of class I MHC expression on HDMEC (upper row) and HMEC-1 (lower row) by INF␣ as determined by fluorescence flow cytometry. Cells were stimulated with 1000 U/ml for 4 (a), 24 (b), 48 (c), and 72 h (d). (. . .) Isotype control Ig2a without addition of IFN␣, (䡠 䡠 䡠) cells stained with MoAb W6/32 without addition of IFN␣, (- - -) isotype control Ig2a with addition of IFN␣, (—) cells stained with MoAb W6/32 with addition of IFN␣.
HDMEC and HMEC-1 at multiple time and dose points with IFN␣ did not affect the cell surface expression of HLA-DR (data not shown). Influence of IFN␥ on HDMEC and HMEC-1 expression of class I and class II MHC molecules. Upregulation of class I MHC molecules was inducible in a time- and dose-dependent manner by stimulation of both HDMEC and HMEC-1 with IFN␥. Elevated induction of class I MHC expression could be observed at as little as 10 U/ml and was maximal after 48 h cytokine incubation at doses in the range of 100 to 1000 U/ml (data not shown). Whereas IFN␣ and TNF␣ failed to show any influence on class II antigen expression, IFN␥ clearly enhanced HLA-DR expression on cultured HDMEC (data not shown).
DISCUSSION IFN␣ is a cytokine with primarily antiviral and antiproliferative abilities. Nevertheless, IFN␣ is also known to display immunomodulatory effects since it regulates the expression of membrane proteins and augments the cytotoxic activity of effector cells [3]. The influence of IFN␣ on expression of class I and
Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.
particularly class II MHC antigens has been examined in detail on large-vessel EC [9], but it has not been examined on microvascular EC. In this paper, we have therefore examined the effect of IFN␣ on class I MHC expression on HDMEC. In our experiments, IFN␣ was able to upregulate class I MHC molecules both on normal primary microvascular EC, isolated from human foreskins, and on transformed microvascular EC, established by Ades et al. [1], in a dose- and time-dependent manner without inducing class II MHC surface expression. In fact, these two different microvascular EC lines expressed elevated surface levels of MHC class I antigens to similar degrees with absolute amounts noted after 48 h cytokine incubation at doses up to 100 U/ml as shown in Figs. 1 and 2. Studies attempting to delineate the roles of various cytokines in modulation of class I MHC expression on microvascular EC are limited. Swerlick et al. [12] and Ruszczak et al. [10] have employed profoundly the influence of INF␥ and TNF␣ on class I and class II MHC expression on HDMEC, but none of these studies have explored that of INF␣. We have demonstrated for the first time that INF␣ alone is a potent inducer of class I MHC on microvascular EC.
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There is convincing evidence for a primary involvement of IFN␣ in the development of autoimmune diseases [6]. Endogenous IFN␣ was found in high frequency in the sera of the majority of SLE patients. Furthermore, a connection between IFN␣ therapy and induction of a SLE-like syndrome is supposed. Perhaps the most interesting finding was that sera from patients with SLE selectively upregulated IFN␣-mediated HUVEC expression of class I MHC antigens [4]. Accordingly, it is conceivable that IFN␣ mediates the induction and/or perpetuation of the vascular damage occurring in SLE, preferentially at the level of the microvasculature, by upregulating MHC class I expression on EC, which now facilitates leukocyte traffic and, as “visible” targets, the immune attack of these immigrated cells. However, direct evidence for these conclusions is as yet lacking. It is known that IFN␣ plays a pivotal role in several virus infections. In this context, our findings may also better explain the important role of IFN␣mediated class I MHC enhancement on microvascular EC in allograft rejection after infection with CMV. Specifically, van Dorp et al. [14] have postulated that CMV infection caused an increase of class I antigen level on the HUVEC surface, which was clearly induced by IFN␣. The results obtained in our study imply that higher levels of class I MHC could have significant consequences for leukocyte recruitment and therefore for the initiation of immune reactions. More importantly, stimulation of class I expression by IFN␣ could enable CMV-infected EC to become more vulnerable to MHC-restricted lysis by cytotoxic T-cells, finally resulting in allograft rejection. Independent confirmation has recently been provided by Miller et al. [5], who found that CMV inhibits IFN␣-stimulated antiviral and immunoregulatory activity, including MHC class I expression on EC, by disrupting the IFN␣ signal transduction pathway. In summary, data shown here represent the first report that IFN␣ induces upregulation of class I MHC expression on human microvascular EC, which might have potential relevance in T-cell-mediated vascular injury in autoimmune disorders as well as allograft rejection after CMV infection.
REFERENCES 1. Ades, E. W., Candal, F. J., Swerlick, R. A., George, V. G., Summers, S., Bosse, D. C., and Lawley, T. J. (1992). HMEC-1: Establishment of an immortalized human microvascular endothelial cell line. J. Invest. Dermatol. 99, 683– 690. 2. Collins, T., Krensky, A. M., Clayberger, C., Fiers, W., Gimbrone, M. A., Jr., Burakoff, S. J., and Pober, J. S. (1984). Human cytolytic T lymphocyte interactions with vascular endothelium and fibroblasts: Role of effector and target cell molecules. J. Immunol. 133, 1878 –1884. 3. Gutterman, J. U. (1994). Cytokine therapeutics: Lessons from interferon alpha. Proc. Natl. Acad. Sci. USA 91, 1198 –1205. 4. Kim, T., Kanayama, Y., Negoro, N., Okamura, M., Takeda, T., and Inoue, T. (1987). Serum levels of interferons in patients with systemic lupus erythematosus. Clin. Exp. Immunol. 70, 562–569. 5. Miller, D. M., Zhang, X., Rahill, B. M., Waldman, W. J., and Sedmark, D. D. (1999). Human cytomegalovirus inhibits IFN␣ stimulated antiviral and immunoregulatory responses by blocking multiple levels of IFN␣ signal transduction. J. Immunol. 162, 6107– 6113. 6. Moutsopoulos, H. M., and Hooks, J. J. (1983). Interferon and autoimmunity. Clin. Exp. Rheumatol. 1, 81– 84. 7. Pober, J. S., and Bimbrone, M. A., Jr. (1982). Expression of Ia-like antigens by human vascular endothelial cells is inducible in vitro: Demonstration by monoclonal antibody binding and immunoprecipitation. Proc. Natl. Acad. Sci. USA 79, 6641– 6645. 8. Pober, J. S., Collins, T., Gimbrone, M. S., Jr., Libby, P., and Reiss, C. S. (1986). Inducible expression of class II major histocompatibility complex antigens and the immunogenicity of vascular endothelium. Transplantation 41, 141–146. 9. Pober, J. S., Gimbrone, M. A., Jr., Lapierre, L. A., Mendrick, D. L., Fiers, W., Rothlein, R., and Springer, T. A. (1986). Overlapping patterns of activation of human endothelial cells by interleukin 1, tumor necrosis factor, and immune interferon. J. Immunol. 137, 1893–1896. 10. Ruszczak, Z., Detmar, M., Imcke, E., and Orfanos, C. E. (1990). Effects of rIFN alpha, beta, and gamma on the morphology, proliferation, and cell surface antigen expression of human dermal microvascular endothelial cells in vitro. J. Invest. Dermatol. 95, 693– 699. 11. Sepp, N. T., Cornelius, L. A., Romani, N., Li, L. J., Caughman, S. W., Lawley, T. J., and Swerlick, R. A. (1995). Polarized expression and basic fibroblast growth factor-induced down-regulation of the alpha 6 beta 4 integrin complex on human microvascular endothelial cells. J. Invest. Dermatol. 104, 266 –270. 12. Swerlick, R. A., Garcia-Gonzalez, E., Kubota, Y., Xu, Y., and Lawley, T. J. (1991). Studies of the modulation of MHC antigen and cell adhesion molecule expression on human dermal microvascular endothelial cells. J. Invest. Dermatol. 97, 190 –196. 13. Swerlick, R. A., Lee, K. H., Li, L. J., Sepp, N. T., Caughman, S. W., and Lawley, T. J. (1992). Regulation of vascular cell adhesion molecule 1 on human dermal microvascular endothelial cells. J. Immunol. 149, 698 –705. 14. Van Dorp, W. T., Jonges, E., Bruggeman, C. A., Daha, M. R., van Es, L. A., and van der Woude, F. J. (1989). Direct induction of MHC class I, but not class II, expression on endothelial cells by cytomegalovirus infection. Transplantation 48, 469 – 472.
Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.
BRIEF COMMUNICATION Upregulation of MHC Class I Molecules on Human Dermal Microvascular Endothelial Cells by Interferon ␣ Van Anh Nguyen, 1 Christina Fu¨rhapter, and Norbert Sepp Department of Dermatology, University of Innsbruck, A-6020 Innsbruck, Austria Received January 29, 2001; published online June 20, 2001
INTRODUCTION Endothelial cells (EC) play a critical role in the induction and modulation of immunologic and nonimmunologic inflammatory processes. As the lining cells of the vasculature, EC are constantly exposed to circulating blood-borne immune effector cells serving as regulators of leukocyte traffic from the intravascular spaces into tissue parenchyma through distinct adherence proteins on the surface of both leukocytes and endothelium [8]. There are significant data demonstrating that proinflammatory cytokines are able to alter the expression of these proteins on EC and, as a result, facilitate their participation in immune responses [9]. It is well recognized that MHC antigens on cells govern the interaction with T-lymphocytes and are involved in the activation of these immune cells [2]. Several authors have reported that, under standard culture conditions, human EC constitutively express class I MHC, but not class II MHC, molecules [7]. 1 To whom correspondence and reprint requests should be addressed at the Department of Dermatology, University of Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria. Fax: 0043/512-504-3017. E-mail: [email protected].
204
In vitro studies examining the expression and regulation of MHC proteins on endothelium were performed predominantly on EC derived from large-vessel human umbilical veins (HUVEC). It is noteworthy that recent studies revealed distinct differences between large-vessel and microvascular EC in regard to cell surface phenotype and cytokine responsiveness [13]. Herein, we have investigated the influence of IFN␣ on the expression of class I MHC antigens on the surface of human dermal microvascular EC (HDMEC) cultured in vitro, using indirect immunofluorescence and FACS quantitation.
MATERIALS AND METHODS Isolation and culture of HDMEC. HDMEC were isolated from surgically removed normal foreskins obtained from newborns and children up to 7 years old according to a modification of a previously described technique [11]. Culture of EC line HMEC-1. The HMEC-1 line was a generous gift from E. W. Ades and propagated as previously described in detail [1]. 0026-2862/01 $35.00 Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.
205
Brief Communication
FIG. 1. Dose response. Upregulation of class I MHC expression on HDMEC (upper row) and HMEC-1 (lower row) by INF␣ as determined by fluorescence flow cytometry. Cells were stimulated for 48 h with 10 (a), 100 (b), and 1000 U/ml (c). (. . .) Isotype control Ig2a without addition of IFN␣, (䡠 䡠 䡠) cells stained with MoAb W6/32 without addition of IFN␣, (- - -) isotype control Ig2a with addition of IFN␣, (—) cells stained with MoAb W6/32 with addition of IFN␣.
Antibodies and cytokines. Hybridomas producing monoclonal antibody (MoAb) W6/32, which recognizes MHC class I molecules, was obtained from the American Type Cell Culture (Rockville, MD). AntiHLA-DR antibody was a gift from Becton–Dickinson (San Jose, CA). MoAb JC 70A and MoAb EN4, which both identify CD31 antigen, were provided by Dako A/S (Glostrup, Denmark) and Harlan Sera-Lab Ltd. (England), respectively. IFN␣ 2a was a gift from Schering Plough Corp. (U.S.A.). IFN␥ and TNF␣ were kindly donated by Dr. G. R. Adolf (Bender & Co., Vienna). FITC-conjugated sheep anti-mouse IgG (Fab)⬘ was obtained from Dako A/S. Cytokine stimulation and fluorescent staining of HDMEC and HMEC-1. HDMEC and HMEC-1 were stimulated with various concentrations of cytokines (10, 100, and 1000 U/ml). Control cultures had only the addition of fresh media. After incubation at 37°C for varying times (4, 24, 48, and 72 h), the cells were exposed to 0.05% trypsin/0.5 mM EDTA (Sigma Chemicals) for 5 min to produce a monodispersed suspension. The harvested cells were washed in PBS with 0.5% BSA (Boehringer Ingelheim, Germany), counted, and aliquoted at 100,000 cells/tube for antibody staining. Unconjugated MoAb were incubated on ice for 30 min with cells. The cells were washed in PBS with 0.5% BSA and counterstained with fluores-
ceinated sheep anti-mouse IgG. After an additional 30 min incubation, the cells were washed as above and resuspended in PBS with 0.5% BSA. Flow-cytometric analysis of HDMEC and HMEC-1. Expression of various EC surface markers was quantitated by flow cytometry using a FACS analyzer (Becton–Dickinson) as described elsewhere [11].
RESULTS Influence of IFN␣ on HDMEC and HMEC-1 expression of class I and class II MHC molecules. Incubation of HDMEC with IFN␣ led to a dose- and timedependent increase of class I MHC expression. Doses as low as 10 U/ml induced a slight upregulation, but maximal expression of class I MHC antigens required doses up to 100 U/ml (Fig. 1). No increase in MHC class I was noted at any dose point at 4 h. Elevation of surface expression started to be evident after 24 h exposure to IFN␣ and was most prominent after 48 h at a dose level of 1000 U/ml (Fig. 2). Treatment of HMEC-1 with IFN␣ resulted in a similar time and dose response, with maximal class I MHC expression being seen after 48 h stimulation under doses up to 100 U/ml (Figs. 1 and 2). In vitro incubation of both
Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.
206
Brief Communication
FIG. 2. Time course. Upregulation of class I MHC expression on HDMEC (upper row) and HMEC-1 (lower row) by INF␣ as determined by fluorescence flow cytometry. Cells were stimulated with 1000 U/ml for 4 (a), 24 (b), 48 (c), and 72 h (d). (. . .) Isotype control Ig2a without addition of IFN␣, (䡠 䡠 䡠) cells stained with MoAb W6/32 without addition of IFN␣, (- - -) isotype control Ig2a with addition of IFN␣, (—) cells stained with MoAb W6/32 with addition of IFN␣.
HDMEC and HMEC-1 at multiple time and dose points with IFN␣ did not affect the cell surface expression of HLA-DR (data not shown). Influence of IFN␥ on HDMEC and HMEC-1 expression of class I and class II MHC molecules. Upregulation of class I MHC molecules was inducible in a time- and dose-dependent manner by stimulation of both HDMEC and HMEC-1 with IFN␥. Elevated induction of class I MHC expression could be observed at as little as 10 U/ml and was maximal after 48 h cytokine incubation at doses in the range of 100 to 1000 U/ml (data not shown). Whereas IFN␣ and TNF␣ failed to show any influence on class II antigen expression, IFN␥ clearly enhanced HLA-DR expression on cultured HDMEC (data not shown).
DISCUSSION IFN␣ is a cytokine with primarily antiviral and antiproliferative abilities. Nevertheless, IFN␣ is also known to display immunomodulatory effects since it regulates the expression of membrane proteins and augments the cytotoxic activity of effector cells [3]. The influence of IFN␣ on expression of class I and
Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.
particularly class II MHC antigens has been examined in detail on large-vessel EC [9], but it has not been examined on microvascular EC. In this paper, we have therefore examined the effect of IFN␣ on class I MHC expression on HDMEC. In our experiments, IFN␣ was able to upregulate class I MHC molecules both on normal primary microvascular EC, isolated from human foreskins, and on transformed microvascular EC, established by Ades et al. [1], in a dose- and time-dependent manner without inducing class II MHC surface expression. In fact, these two different microvascular EC lines expressed elevated surface levels of MHC class I antigens to similar degrees with absolute amounts noted after 48 h cytokine incubation at doses up to 100 U/ml as shown in Figs. 1 and 2. Studies attempting to delineate the roles of various cytokines in modulation of class I MHC expression on microvascular EC are limited. Swerlick et al. [12] and Ruszczak et al. [10] have employed profoundly the influence of INF␥ and TNF␣ on class I and class II MHC expression on HDMEC, but none of these studies have explored that of INF␣. We have demonstrated for the first time that INF␣ alone is a potent inducer of class I MHC on microvascular EC.
207
Brief Communication
There is convincing evidence for a primary involvement of IFN␣ in the development of autoimmune diseases [6]. Endogenous IFN␣ was found in high frequency in the sera of the majority of SLE patients. Furthermore, a connection between IFN␣ therapy and induction of a SLE-like syndrome is supposed. Perhaps the most interesting finding was that sera from patients with SLE selectively upregulated IFN␣-mediated HUVEC expression of class I MHC antigens [4]. Accordingly, it is conceivable that IFN␣ mediates the induction and/or perpetuation of the vascular damage occurring in SLE, preferentially at the level of the microvasculature, by upregulating MHC class I expression on EC, which now facilitates leukocyte traffic and, as “visible” targets, the immune attack of these immigrated cells. However, direct evidence for these conclusions is as yet lacking. It is known that IFN␣ plays a pivotal role in several virus infections. In this context, our findings may also better explain the important role of IFN␣mediated class I MHC enhancement on microvascular EC in allograft rejection after infection with CMV. Specifically, van Dorp et al. [14] have postulated that CMV infection caused an increase of class I antigen level on the HUVEC surface, which was clearly induced by IFN␣. The results obtained in our study imply that higher levels of class I MHC could have significant consequences for leukocyte recruitment and therefore for the initiation of immune reactions. More importantly, stimulation of class I expression by IFN␣ could enable CMV-infected EC to become more vulnerable to MHC-restricted lysis by cytotoxic T-cells, finally resulting in allograft rejection. Independent confirmation has recently been provided by Miller et al. [5], who found that CMV inhibits IFN␣-stimulated antiviral and immunoregulatory activity, including MHC class I expression on EC, by disrupting the IFN␣ signal transduction pathway. In summary, data shown here represent the first report that IFN␣ induces upregulation of class I MHC expression on human microvascular EC, which might have potential relevance in T-cell-mediated vascular injury in autoimmune disorders as well as allograft rejection after CMV infection.
REFERENCES 1. Ades, E. W., Candal, F. J., Swerlick, R. A., George, V. G., Summers, S., Bosse, D. C., and Lawley, T. J. (1992). HMEC-1: Establishment of an immortalized human microvascular endothelial cell line. J. Invest. Dermatol. 99, 683– 690. 2. Collins, T., Krensky, A. M., Clayberger, C., Fiers, W., Gimbrone, M. A., Jr., Burakoff, S. J., and Pober, J. S. (1984). Human cytolytic T lymphocyte interactions with vascular endothelium and fibroblasts: Role of effector and target cell molecules. J. Immunol. 133, 1878 –1884. 3. Gutterman, J. U. (1994). Cytokine therapeutics: Lessons from interferon alpha. Proc. Natl. Acad. Sci. USA 91, 1198 –1205. 4. Kim, T., Kanayama, Y., Negoro, N., Okamura, M., Takeda, T., and Inoue, T. (1987). Serum levels of interferons in patients with systemic lupus erythematosus. Clin. Exp. Immunol. 70, 562–569. 5. Miller, D. M., Zhang, X., Rahill, B. M., Waldman, W. J., and Sedmark, D. D. (1999). Human cytomegalovirus inhibits IFN␣ stimulated antiviral and immunoregulatory responses by blocking multiple levels of IFN␣ signal transduction. J. Immunol. 162, 6107– 6113. 6. Moutsopoulos, H. M., and Hooks, J. J. (1983). Interferon and autoimmunity. Clin. Exp. Rheumatol. 1, 81– 84. 7. Pober, J. S., and Bimbrone, M. A., Jr. (1982). Expression of Ia-like antigens by human vascular endothelial cells is inducible in vitro: Demonstration by monoclonal antibody binding and immunoprecipitation. Proc. Natl. Acad. Sci. USA 79, 6641– 6645. 8. Pober, J. S., Collins, T., Gimbrone, M. S., Jr., Libby, P., and Reiss, C. S. (1986). Inducible expression of class II major histocompatibility complex antigens and the immunogenicity of vascular endothelium. Transplantation 41, 141–146. 9. Pober, J. S., Gimbrone, M. A., Jr., Lapierre, L. A., Mendrick, D. L., Fiers, W., Rothlein, R., and Springer, T. A. (1986). Overlapping patterns of activation of human endothelial cells by interleukin 1, tumor necrosis factor, and immune interferon. J. Immunol. 137, 1893–1896. 10. Ruszczak, Z., Detmar, M., Imcke, E., and Orfanos, C. E. (1990). Effects of rIFN alpha, beta, and gamma on the morphology, proliferation, and cell surface antigen expression of human dermal microvascular endothelial cells in vitro. J. Invest. Dermatol. 95, 693– 699. 11. Sepp, N. T., Cornelius, L. A., Romani, N., Li, L. J., Caughman, S. W., Lawley, T. J., and Swerlick, R. A. (1995). Polarized expression and basic fibroblast growth factor-induced down-regulation of the alpha 6 beta 4 integrin complex on human microvascular endothelial cells. J. Invest. Dermatol. 104, 266 –270. 12. Swerlick, R. A., Garcia-Gonzalez, E., Kubota, Y., Xu, Y., and Lawley, T. J. (1991). Studies of the modulation of MHC antigen and cell adhesion molecule expression on human dermal microvascular endothelial cells. J. Invest. Dermatol. 97, 190 –196. 13. Swerlick, R. A., Lee, K. H., Li, L. J., Sepp, N. T., Caughman, S. W., and Lawley, T. J. (1992). Regulation of vascular cell adhesion molecule 1 on human dermal microvascular endothelial cells. J. Immunol. 149, 698 –705. 14. Van Dorp, W. T., Jonges, E., Bruggeman, C. A., Daha, M. R., van Es, L. A., and van der Woude, F. J. (1989). Direct induction of MHC class I, but not class II, expression on endothelial cells by cytomegalovirus infection. Transplantation 48, 469 – 472.
Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.