Elevated Serum Levels of Interleukin-6 in Paraneoplastic Pemphigus

To the Editor: Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous blistering disease associated with a unique group of underlying neoplasms (Anhalt et al., 1990Anhalt G.J. Kim S.-C. Stanley J.R. et al.Paraneoplastic pemphigus: an autoimmune mucocutaneous disease associated with neoplasia.New Engl J Med. 1990; 323: 1729-1735Crossref PubMed Scopus (837) Google Scholar). These neoplasms are almost exclusively comprised of B cell lymphoproliferative diseases including non-Hodgkin’s lymphoma, chronic lymphocytic leukemia (CLL), Castleman’s disease (CD), thymoma, and Waldenstrom’s macroglobulinemia (Anhalt, 1997Anhalt G.J. Paraneoplastic pemphigus.Adv Dermatol. 1997; 12: 77-96PubMed Google Scholar). The sera of PNP patients contain autoantibodies against plakin-proteins (desmoplakins, BPAg1, envoplakin, periplakin, and plectin) (Oursler et al., 1992Oursler J.R. Labib R.S. Ariss-Abdo L. Burke T. O’Keefe W.J. Anhalt G.J. Human autoantibodies against desmoplakins in paraneoplastic pemphigus.J Clin Invest. 1992; 89: 1775-1782Crossref PubMed Scopus (150) Google Scholar;Kim et al., 1997Kim S.-C. Kwon Y.D. Lee I.J. Chang S.N. Lee T.G. cDNA cloning of the 210 kDa paraneoplastic pemphigus antigen reveals that envoplakin is a component of the antigen complex.J Invest Dermatol. 1997; 109: 365-369Abstract Full Text PDF PubMed Scopus (83) Google Scholar;Borradori et al., 1998Borradori L. Trueb R.M. Jaunin F. Limat A. Favre B. Saurat J.H. Autoantibodies from a patient with paraneoplastic pemphigus bind periplakin, a novel member of the plakin family.J Invest Dermatol. 1998; 111: 338-340Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar;Mahoney et al., 1998Mahoney M.G. Aho S. Uitto J. Stanley J.R. The members of the plakin family of proteins recognized by paraneoplastic pemphigus antibodies include periplakin.J Invest Dermatol. 1998; 38: 308-313Abstract Full Text Full Text PDF Scopus (121) Google Scholar), desmogleins 3 and 1 (Amagai et al., 1998Amagai M. Nishikawa T. Nousari H.C. Anhalt G.J. Hashimoto T. Antibodies against desmoglein 3 (pemphigus vulgaris antigen) are present in sera from patients with paraneoplastic pemphigus and cause acantholysis in vivo in neonatal mice.J Clin Invest. 1998; 102: 775-782Crossref PubMed Scopus (255) Google Scholar), and a yet unidentified 170 kDa antigen. Cell-mediated autoimmunity is also involved in the pathogenesis of PNP (Anhalt, 1997Anhalt G.J. Paraneoplastic pemphigus.Adv Dermatol. 1997; 12: 77-96PubMed Google Scholar), although the mechanisms underlying this component of the disease are yet undetermined. It has been suggested that interleukin-6 (IL-6) may play a crucial role in the pathogenesis of certain autoimmune diseases (Papanicolaou et al., 1998Papanicolaou D.A. Wilder R.L. Manolagas S.C. Chrousos G.P. The pathophysiologic roles of interleukin-6 in human disease.Ann Int Med. 1998; 128: 127-137Crossref PubMed Scopus (947) Google Scholar). IL-6, synthesized by lymphoid and nonlymphoid cells, has a variety of functions, including differentiation and maturation of B and T lymphocytes, as well as the production of immunoglobulins and acute phase reactants (Papanicolaou et al., 1998Papanicolaou D.A. Wilder R.L. Manolagas S.C. Chrousos G.P. The pathophysiologic roles of interleukin-6 in human disease.Ann Int Med. 1998; 128: 127-137Crossref PubMed Scopus (947) Google Scholar). Enhanced expression of IL-6 has been observed in subpopulations of tumors or cell lines from each of the neoplasms associated with PNP (Yabuhara et al., 1989Yabuhara A. Yanagisawa M. Murata T. et al.Giant lymph node hyperplasia (Castleman’s Disease) with spontaneous production of high levels of B-cell differentiation factor activity.Cancer. 1989; 63: 260-265Crossref PubMed Scopus (42) Google Scholar;Cicco et al., 1991Cicco N. Lubbert M. Oster W. Lindemann A. Mertelsmann R. Cytokines in the pathogenesis and management of Non-Hodgkin’s Lymphomas.Hematol Oncol Clin North Am. 1991; 5: 1053-1066PubMed Google Scholar;Lahat et al., 1991Lahat N. Aghai E. Maroun B. Kinarty A. Quitt M. Froom P. Increased spontaneous secretion of IL-6 from B-cells of patients with B chronic lymphatic leukemia (B-CLL) and autoimmunity.Clin Exp Immunol. 1991; 85: 302-306Crossref PubMed Scopus (19) Google Scholar;Nachbaur et al., 1991Nachbaur D.M. Herold M. Maneschj A. Huber H. Serum levels of interleukin-6 in multiple myeloma and other hematological disorders: correlation with disease activity and other prognostic parameters.Ann Hematol. 1991; 62: 54-58Crossref PubMed Scopus (109) Google Scholar), and non-Hodgkin’s lymphomas, CLL, and CD are known to be complicated by autoimmune phenomena. For example, in CLL, 3% of patients will develop autoimmune thrombocytopenia, 6% will develop pure red cell aplasia, and as many as 11% will develop Coomb’s positive hemolytic anemia (Diehl and Ketchum, 1998Diehl L.F. Ketchum L.H. Autoimmune disease and chronic lymphocytic leukemia. autoimmune hemolytic anemia, pure red cell aplasia, and autoimmune thrombocytopenia.Semin Oncol. 1998; 25: 80-97PubMed Google Scholar). These same tumors are known to be associated with high serum levels of IL-6, and although elevations of serum IL-6 have been correlated with B-symptoms and poor outcomes (Fayad et al., 1998Fayad L. Cabanillas F. Talpaz M. McLaughlin P. Kurzrock R. High serum interleukin-6. levels correlate with a shorter failure-free survival in indolent lymphoma.Leuk Lymphoma. 1998; 30: 563-571PubMed Google Scholar), there has been no direct correlative study, examining the link between increased serum IL-6 and development of autoimmune disease. We hypothesize that this same group of tumors may promote autoimmunity against desmogleins and plakin proteins (resulting in paraneoplastic pemphigus), as opposed to the more commonly observed autoimmune response against hematopoietic cell antigens, and in PNP this may be associated with increased serum levels of IL-6. All of these observations, plus reported evidence that interferon alpha, a potent enhancer of IL-6 expression (Jourdan et al., 1991Jourdan M. Zhang X.G. Portier M. Boiron J.M. Bataille R. Klein B. IFN-alpha induces autocrine production of IL-6 in myeloma cell lines.J Immunol. 1991; 147: 4402-4407PubMed Google Scholar;Papanicolaou et al., 1998Papanicolaou D.A. Wilder R.L. Manolagas S.C. Chrousos G.P. The pathophysiologic roles of interleukin-6 in human disease.Ann Int Med. 1998; 128: 127-137Crossref PubMed Scopus (947) Google Scholar), has been associated with triggering PNP (Kirsner et al., 1995Kirsner R.S. Anhalt G.J. Kerdel F.A. Treatment with alpha interferon associated with the development of paraneoplastic pemphigus.Br J Dermatol. 1995; 132: 474-478Crossref PubMed Scopus (53) Google Scholar), led us to evaluate the possible role of IL-6 in the pathogenesis of PNP. Sera from 33 PNP patients were analyzed for IL-6 by enzyme-linked immunosorbent assay using commercially available kits (BioSource International, Camarillo, CA). Control sera (N=81) included 32 from pemphigus vulgaris and foliaceus patients (eight with malignancies), 23 from bullous and cicatricial pemphigoid patients, 10 from systemic lupus erythematosus patients, and five from individual cases of lichen planus and multiple myeloma, CLL and discoid lupus erythematosus, CLL and an uncharacterized bullous eruption, pemphigus erythematosus, and erythema multiforme with chronic myelocytic leukemia. Eleven sera with negative antinuclear antibodies were used as normal controls. IL-6 elevation above 10 pg per ml was seen in 22 (67%) of the 33 PNP patients, with a mean serum concentration of 134 pg per ml (range 2–820 pg per ml). Of these, 14 had levels more than three times the upper limit of normal (mean normal serum IL-6 levels < 3 pg per ml, range 0–10.09 pg per ml), and eight had levels greater than 100 pg per ml (Figure 1). All tumor types were represented in this group. The 14 patients with markedly elevated IL-6 levels had a particularly aggressive clinical course, most dying within a few months of diagnosis. None of these patients had known confounding processes that would account for elevated IL-6 levels at the time the sample was obtained (e.g., sepsis, infection, etc.). By contrast, elevated serum IL-6 was seen in only nine (11%) of the 81 control sera (range 2–139.2 pg per ml) (mean IL-6 8.3 ± 15.3 pg per ml). Seven had an associated blistering disorder (four bullous pemphigoid, one pemphigus vulgaris, one pemphigus vulgaris with gastric adenocarcinoma, and one CLL with an unspecified blistering disorder) (range 17–139.2 pg per ml). One patient with lupus erythematosus and another with CLL and discoid lupus erythematosus also had elevated IL-6. Normal controls all had IL-6 levels at or below 6 pg per ml. Using two-tailed t tests, the mean IL-6 value was significantly higher in PNP patients (n = 33, mean 86.7 ± 185.4) than those with other blistering disorders associated with malignancy (n = 8, mean 10.4 ± 13.0, p = 0.025), other blistering diseases in general (n = 49, mean 9.1 ± 17.3, p = 0.022), lupus erythematosus (n = 10, mean 4.9 ± 15.4, p = 0.022), normal controls (n = 11, mean 3.2 ± 1.5, p = 0.014), and all cases in the control group combined (n = 81, mean 8.3 ± 15.3, p = 0.020). Moreover, using a two-tailed t test for proportions, the incidence of elevated IL-6 (>0 pg per ml) is significantly higher in PNP (22 of 33) than that in the control group (nine of 81, p = 2.0 × 10–8), other blistering disorders (seven of 49, p = 5.6 × 10–6), other blistering disorders associated with malignancy (one of eight, p = 0.009), and normal controls (none of 11, p = 4.2 × 10–4). This supports the concept of cytokine dysregulation in PNP (Yoshizaki et al., 1989Yoshizaki K. Matsuda T. Nishimoto N. et al.Pathogenic significance of interleukin-6 (IL-6/BSF-2) in Castleman’s disease.Blood. 1989; 74: 1360-1367Crossref PubMed Google Scholar;Carrington et al., 1990Carrington P.A. Anderson H. Harris M. Walsh S.E. Houghton J.B. Morgenstern G.R. Autoimmune cytopenias in Castleman’s disease.Am J Clin Pathol. 1990; 94: 101-104PubMed Google Scholar). In this study we demonstrate elevated serum IL-6 levels in the majority of cases of PNP. The prompt normalization of certain autoimmune and inflammatory phenomena upon excision of CD parallels the normalization of IL-6 levels, and the administration of anti-IL-6 antibodies has been effective for CD-associated autoimmune phenomena (Beck et al., 1994Beck J.T. Hsu S.M. Wijdenes J. et al.Alleviation of systemic manifestations of Castleman’s disease by monoclonal anti-interleukin-6 antibody.New Engl J Med. 1994; 330: 602-605Crossref PubMed Scopus (297) Google Scholar). Cytogenetic studies of CD cells has been associated with a 7;14 translocation (Nakamura et al., 1993Nakamura H. Nakaseko C. Ishii A. et al.Chromosomal abnormalities in Castleman’s disease with high levels of serum interleukin-6.Rinsho Ketsueki – Jap J Clin Hematol. 1993; 34: 212-217PubMed Google Scholar). This is of significance because the IL-6 gene is located on 7p21–22 and the immunoglobulin heavy gene enhancer resides on chromosome 14, potentially explaining the high levels of IL-6 produced by CD tumors. Also mice with hematopoietic cells that have been altered using a retroviral vector bearing the murine IL-6 coding sequences to yield dysregulated IL-6 overexpression, produce a syndrome resembling CD (Brandt et al., 1990Brandt S.J. Bodine D.M. Dunbar C.E. Nienhuis A.W. Dysregulated interleukin-6 expression produces a syndrome resembling Castleman’s disease in mice.J Clin Invest. 1990; 86: 592-599Crossref PubMed Scopus (291) Google Scholar). The role of IL-6 in autoimmune diseases including PNP is intriguing. However, further studies are necessary to determine if this cytokine originates from the associated neoplams or from PNP reactive lymphocytes, and if dysregulation of other cytokines are also present in this disease. We acknowledge the assistance of Dr. Steven Brottman in the performance of the IL-6 assays.