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ICAM-1 in cerulein-induced pancreatitis
748 CORRESPONDENCE
ICAM-1 in Cerulein-Induced Pancreatitis Dear Sir: Steer and colleagues have long championed premature trypsin activation as the critical early event in cerulein-induced pancreatitis. They recently turned their attention to what is central to injury in this model: neutrophil recruitment, first regarding platelet-activating factor (PAF)1 and now the intercellular adhesion molecule 1 (ICAM1).2 However, they make no mention of previous studies showing PAF as a promoter of ICAM-1 expression,3,4 possibly because their previous work using a PAF inhibitory enzyme (acetylhydrolase) produced only a modest reduction of injury in the cerulein model.1 However, Sandoval et al.,5 using a specific PAF inhibitor BN 52021, were able to entirely prevent neutrophil recruitment, edema, and acinar cell necrosis in the cerulein model. Unlike ICAM-1, an endothelial cell product, PAF is produced directly from the acinar cell membrane in response to a supramaximal dose of cerulein from activation6 of a calcium-dependent phospholipase A2, in the absence of any known contribution from intracellular trypsin activation. One anticipates that when finally studied in the cerulein model, PAF levels will be highly correlated with ICAM-1 expression as part of the mechanism of neutrophil recruitment. Sandoval et al.5 have already shown that the recruitment of neutrophils is critical for acinar cell necrosis to occur in the cerulein model5; the presence or absence of neutrophils,5 when studied using the appropriate stain for apoptosis, determined the nature of acinar cell injury, i.e., necrosis (when neutrophils are present) or apoptosis (in the absence of neutrophils). With the neutropenia produced with antineutrophil serum (ⱕ250 neutrophils), Sandoval et al.5 found that necrosis was entirely lost, with only apoptosis present. By contrast, in the Beth Israel group’s study, the neutropenic animals had no apoptosis but only a reduction in the percentage of the acinar cell necrosis (25%–15%).2 However, they failed to perform the appropriate Hoechst stain for apoptosis.5 This calls into serious question the method of Frossard et al.2 in detecting ‘‘necrosis’’: ‘‘. . . an experienced morphologist who is not aware of the sample identity.’’ By contrast, Sandoval et al.5 used the Hoechst stain quantification of apoptosis as well as strict criteria for necrosis: ‘‘. . . swollen cytoplasm, loss of plasma cell membrane integrity, and leakage of organelles into the interstitial space.’’ Previously, in the opossum model, the original estimate of Steer and colleagues of ‘‘early acinar necrosis’’ (40%) at 7 days was shown to be highly inflated7 when a more precise methodology for establishing the presence both of necrosis and apoptosis was used,8 with true necrosis at 7 days being only 11% rather than 40%. The above objections aside, one looks forward to future studies on the link between PAF and ICAM-1 in the cerulein model, with ICAM-1 being part of the mechanism by which PAF recruits neutrophils to cause acinar cell necrosis. Such studies will go a long way in advancing our understanding of necrosis cerulein model as being more than simply the result of premature trypsin activation, which itself may prove to be an interesting but irrelevant epiphenomenon. It is much more likely that cerulein causes acinar cell necrosis beginning with the release of PAF directly from acinar cell membranes, which in turn promotes endothelial ICAM-1 expression; this, possibly in concert with other cytokines, leads to recruitment and activation of neutrophils. MICHAEL O. BLACKSTONE, M.D. Section of Gastroenterology Department of Medicine University of Chicago Chicago, Illinois
GASTROENTEROLOGY Vol. 117, No. 3
1. Hofbauer B, Saluja AK, Bhatia M, et al. Effect of recombinant platelet-activating factor acetylhydrolase on two models of experimental acute pancreatitis. Gastroenterology 1998;115:1238– 1247. 2. Frossard JL, Saluja A, Bhagat L, et al. The role of intercellular adhesion molecule 1 and neutrophils in acute pancreatitis and pancreatitis-associated lung injury. Gastroenterology 1999;116: 694–701. 3. Chihara J, Maruyama I, Yasuba H, et al. Possible induction of intercellular adhesion molecule-1 (ICAM-1) expression on endothelial cells by platelet-activating factor (PAF). J Lipid Mediat 1992;5: 159–162. 4. Beyer A. PAF and CD18 mediate neutrophil infiltration in upper gastrointestinal tract during intra-abdominal sepsis. Am J Physiol 1998;275:G467–G472. 5. Sandoval D, Gukovskaya A, Reavey P, et al. The role of neutrophils and platelet-activating factor in mediating experimental pancreatitis. Gastroenterology 1996;111:1081–1091. 6. Zhou W, Levine BA, Olson MS. Platelet-activating factor: a mediator of pancreatic inflammation during cerulein hyperstimulation. Am J Pathol 1993;142:1504–1512. 7. Lerch MM, Saluja AK, Runzi M, et al. Pancreatic duct obstruction triggers acute necrotizing pancreatitis in the opossum [see comments]. Gastroenterology 1993;104:853–861. 8. Gukovskaya AS, Perkins P, Zaninovic V, et al. Mechanisms of cell death after pancreatic duct obstruction in the opossum and the rat. Gastroenterology 1996;110:875–884.
Reply. We thank Dr. Blackstone for his comments on our work on the pathophysiology of acute pancreatitis. We, indeed, have long championed the hypothesis that premature intra-acinar cell activation of trypsinogen is a critical early event in the development of acute pancreatitis. Our studies have used several different models of pancreatitis including the one induced by cerulein. Recent publications both from our group1,2 and that of Dr. Gorelick3 have provided what we believe is direct evidence in support of this hypothesis. In these in vitro studies, stimulation of rat pancreatic acini with a supramaximally stimulating dose of cerulein resulted not only in activation of digestive enzyme zymogens but also acinar cell injury. Inhibition of trypsin activity in these experiments prevented ceruleininduced acinar cell injury, thus clearly showing that premature activation of digestive enzyme zymogens can lead to the acinar cell injury observed during cerulein-induced pancreatitis. However, as we have pointed out in several of our recent publications, we believe that only the ‘‘initial injury’’ to the gland during pancreatitis is caused by the premature activation of digestive enzyme zymogens. The ultimate severity of the disease is determined by events that occur subsequent to the initial acinar cell injury. The exact nature of these events is the subject of intense ongoing investigations. They probably involve a variety of factors including cytokines, chemokines, PAF, oxygenderived free radicals, apoptosis, and necrosis. We4 and others have recently shown that substance P acting via neurokinin (NK-1) receptors, chemokines interacting with CCR1 receptors, ICAM-1, PAF, tumor necrosis factor ␣, several different interleukins, as well as complement system play an important role in determining the severity of pancreatitis both clinically and in animal models. Certainly, this list will expand in the near future. There could be several reasons for the different findings in our study5 compared with those of Sandoval et al.6 dealing with the role of PAF during pancreatitis. Sandoval et al. have reported almost complete prevention of pancreatitis using a PAF receptor antagonist, whereas in our studies, in which PAF was neutralized by its hydrolysis with PAF-acetylhydolase, we found only partial but significant
September 1999
protection. The 2 studies differed in other important experimental details. Of note, a recent announcement from British Biotech indicates that their PAF-receptor antagonist Lexipafant was not effective against pancreatitis in a large multicenter clinical trial. In the opossum duct ligation model, we routinely observe morphological acinar cell injury/necrosis that is significantly more extensive than the 11% reported by Gukovskaya et al.7 We do not know the reason for these differences, but they are certainly not due to our inability to detect apoptosis in this model because neither we8 nor Gukovskaya et al.7 have found evidence of significant apoptosis after 7 days of duct ligation in opossums. Dr. Blackstone is correct in pointing out that PAF might regulate ICAM-1 expression and, as a result, the neutrophil sequestration in the pancreas that is observed during pancreatitis. We are in the process of studying such interactions. However, we do not believe that PAF and ICAM-1 are the only players in this game. Sandoval et al.,6 in the article referred to by Dr. Blackstone, state that ‘‘. . . [we] hypothesize that an initial pancreatic injury causes expression of PAF that mediates activation and infiltration of neutrophils in the tissues [during pancreatitis].’’ We basically agree with this hypothesis but would argue that the initial pancreatic injury referred to by Sandoval et al. is the result of premature activation of digestive enzyme zymogens within pancreatic acinar cells. ASHOK K. SALUJA, Ph.D. MICHAEL L. STEER, M.D. Beth Israel Deaconess Medical Center Harvard Medical School Boston, Massachusetts 1. Saluja AK, Donovan EA, Yamanaka K, et al. Caerulein-induced in vitro activation of trypsinogen in rat pancreatic acini is mediated by cathepsin B. Gastroenterology 1997;113:304–310. 2. Saluja A, Bhagat L, Lee H, et al. Role of calcium in CCK-induced trypsinogen activation and acinar cell injury. Am J Physiol 1998. 3. Grady T, Mah’Moud M, Otani T, et al. Zymogen proteolysis within the pancreatic acinar cell is associated with cellular injury. Am J Physiol 1998;275:G1010–G1017. 4. Saluja A, Steer M. Pathophysiology of pancreatitis: role of cytokines and other mediators. Digestion 1998;60:27–33. 5. Hofbauer B, Saluja A, Bhatia M, et al. Effect of recombinant platelet-activating factor acetylhydrolase on two models of experimental acute pancreatitis. Gastroenterology 1998;115:1238–1247. 6. Sandoval D, Gukovskaya A, Reavey P, et al. The role of neutrophils and platelet-activating factor in mediating experimental pancreatitis. Gastroenterology 1996;111:1081–1091. 7. Gukovskaya AS, Perkins P, Zaninvic V, et al. Mechanisms of cell death after pancreatic duct obstruction in opossum and rat. Gastroenterology 1996;110:875–884. 8. Kaiser A, Saluja A, Sengupta A, et al. Relationship between severity, necrosis and apoptosis in five models of experimental acute pancreatitis. Am J Physiol 1995;38:C1295–C1304.
CORRESPONDENCE 749
enteropathy are gluten dependent. Anticonnective tissue antibodies were first described in DH1 and subsequently found in celiac disease. It was suggested that reticulin or another connective tissue antigen may be the autoantigen in DH and celiac disease. Recently, tissue transglutaminase (TTG) was suggested to be the autoantigen in celiac disease.2 A very high incidence of tissue transglutaminase antibodies (TTA) was subsequently found in patients with celiac disease.3,4 We now report our findings on TTA in DH and the effect of gluten withdrawal on these antibodies. Seventy-two patients with DH and 18 controls (with other autoimmune bullous diseases, cicatricial pemphigoid, pemphigus, and linear IgA disease) were studied. DH was confirmed in all patients by the presence of IgA in the dermal papillae, and 67 had intestinal biopsy specimens. Thirty-seven of the patients had been on a strict gluten-free diet (GFD) for more than 2 years; 20 on a partial GFD, defined as patients knowingly consuming gluten-containing food but not more frequently than once a week; and 15 on a normal diet. Serum was screened for IgA antiendomysial antibody (AEA) at a dilution of 1/5 with umbilical cord as substrate. IgA TTA was screened for by an enzyme-linked immunosorbent assay (ELISA kit; Inova Diagnostics, San Diego, CA) using guinea pig liver TT antigen and goat anti-human IgA. Sample values were calculated as recommended by the manufacturer; a positive result was indicated by a unit value greater than 20. Appropriate positive and negative (no serum) controls were included. Figure 1 shows the titers of TTA measured in the patients with DH. Among the 15 patients consuming a normal diet, AEA was detected in 10 (67%) and TTA in 12 (75%). All 10 patients who had AEA were TTA positive, 2 had TTA alone, and 3 had neither antibody. Among the 20 patients on a partial GFD, AEA was present in 5 (25%) and TTA in 7 (35%). Again, there was a good correlation between the presence of AEA and TTA. In all 5 patients who had AEA, TTA was also present. Among the 37 patients on a strict GFD for at least 2 years, AEA was not present in any but TTA was present in 1 patient. One of the 18 control patients with bullous disease, who had cicatricial pemphigoid, had a positive TTA. Small intestinal biopsy specimens were obtained from 13 of the 15 patients on a normal diet. The 2 patients who declined to undergo biopsy both had TTA and AEA. Nine of the 13 specimens showed
Tissue Transglutaminase Antibodies in Dermatitis Herpetiformis Dear Sir: Dermatitis herpetiformis (DH) has a characteristic rash, and the hallmark of the disease is immunoglobulin (Ig) A deposits in the dermal papillae. Two thirds of patients have an enteropathy indistinguishable from celiac disease, and the remaining third have associated features of gluten sensitivity (increased intraepithelial lymphocyte [IEL] count and/or increase of ␥/⌬ T cells). Both the rash and the
Figure 1. TTA in patients with DH in relation to diet. Antibodies were measured using a specific ELISA. Results are expressed as optical density at 450 nm; values below 20 were considered negative.
ICAM-1 in Cerulein-Induced Pancreatitis Dear Sir: Steer and colleagues have long championed premature trypsin activation as the critical early event in cerulein-induced pancreatitis. They recently turned their attention to what is central to injury in this model: neutrophil recruitment, first regarding platelet-activating factor (PAF)1 and now the intercellular adhesion molecule 1 (ICAM1).2 However, they make no mention of previous studies showing PAF as a promoter of ICAM-1 expression,3,4 possibly because their previous work using a PAF inhibitory enzyme (acetylhydrolase) produced only a modest reduction of injury in the cerulein model.1 However, Sandoval et al.,5 using a specific PAF inhibitor BN 52021, were able to entirely prevent neutrophil recruitment, edema, and acinar cell necrosis in the cerulein model. Unlike ICAM-1, an endothelial cell product, PAF is produced directly from the acinar cell membrane in response to a supramaximal dose of cerulein from activation6 of a calcium-dependent phospholipase A2, in the absence of any known contribution from intracellular trypsin activation. One anticipates that when finally studied in the cerulein model, PAF levels will be highly correlated with ICAM-1 expression as part of the mechanism of neutrophil recruitment. Sandoval et al.5 have already shown that the recruitment of neutrophils is critical for acinar cell necrosis to occur in the cerulein model5; the presence or absence of neutrophils,5 when studied using the appropriate stain for apoptosis, determined the nature of acinar cell injury, i.e., necrosis (when neutrophils are present) or apoptosis (in the absence of neutrophils). With the neutropenia produced with antineutrophil serum (ⱕ250 neutrophils), Sandoval et al.5 found that necrosis was entirely lost, with only apoptosis present. By contrast, in the Beth Israel group’s study, the neutropenic animals had no apoptosis but only a reduction in the percentage of the acinar cell necrosis (25%–15%).2 However, they failed to perform the appropriate Hoechst stain for apoptosis.5 This calls into serious question the method of Frossard et al.2 in detecting ‘‘necrosis’’: ‘‘. . . an experienced morphologist who is not aware of the sample identity.’’ By contrast, Sandoval et al.5 used the Hoechst stain quantification of apoptosis as well as strict criteria for necrosis: ‘‘. . . swollen cytoplasm, loss of plasma cell membrane integrity, and leakage of organelles into the interstitial space.’’ Previously, in the opossum model, the original estimate of Steer and colleagues of ‘‘early acinar necrosis’’ (40%) at 7 days was shown to be highly inflated7 when a more precise methodology for establishing the presence both of necrosis and apoptosis was used,8 with true necrosis at 7 days being only 11% rather than 40%. The above objections aside, one looks forward to future studies on the link between PAF and ICAM-1 in the cerulein model, with ICAM-1 being part of the mechanism by which PAF recruits neutrophils to cause acinar cell necrosis. Such studies will go a long way in advancing our understanding of necrosis cerulein model as being more than simply the result of premature trypsin activation, which itself may prove to be an interesting but irrelevant epiphenomenon. It is much more likely that cerulein causes acinar cell necrosis beginning with the release of PAF directly from acinar cell membranes, which in turn promotes endothelial ICAM-1 expression; this, possibly in concert with other cytokines, leads to recruitment and activation of neutrophils. MICHAEL O. BLACKSTONE, M.D. Section of Gastroenterology Department of Medicine University of Chicago Chicago, Illinois
GASTROENTEROLOGY Vol. 117, No. 3
1. Hofbauer B, Saluja AK, Bhatia M, et al. Effect of recombinant platelet-activating factor acetylhydrolase on two models of experimental acute pancreatitis. Gastroenterology 1998;115:1238– 1247. 2. Frossard JL, Saluja A, Bhagat L, et al. The role of intercellular adhesion molecule 1 and neutrophils in acute pancreatitis and pancreatitis-associated lung injury. Gastroenterology 1999;116: 694–701. 3. Chihara J, Maruyama I, Yasuba H, et al. Possible induction of intercellular adhesion molecule-1 (ICAM-1) expression on endothelial cells by platelet-activating factor (PAF). J Lipid Mediat 1992;5: 159–162. 4. Beyer A. PAF and CD18 mediate neutrophil infiltration in upper gastrointestinal tract during intra-abdominal sepsis. Am J Physiol 1998;275:G467–G472. 5. Sandoval D, Gukovskaya A, Reavey P, et al. The role of neutrophils and platelet-activating factor in mediating experimental pancreatitis. Gastroenterology 1996;111:1081–1091. 6. Zhou W, Levine BA, Olson MS. Platelet-activating factor: a mediator of pancreatic inflammation during cerulein hyperstimulation. Am J Pathol 1993;142:1504–1512. 7. Lerch MM, Saluja AK, Runzi M, et al. Pancreatic duct obstruction triggers acute necrotizing pancreatitis in the opossum [see comments]. Gastroenterology 1993;104:853–861. 8. Gukovskaya AS, Perkins P, Zaninovic V, et al. Mechanisms of cell death after pancreatic duct obstruction in the opossum and the rat. Gastroenterology 1996;110:875–884.
Reply. We thank Dr. Blackstone for his comments on our work on the pathophysiology of acute pancreatitis. We, indeed, have long championed the hypothesis that premature intra-acinar cell activation of trypsinogen is a critical early event in the development of acute pancreatitis. Our studies have used several different models of pancreatitis including the one induced by cerulein. Recent publications both from our group1,2 and that of Dr. Gorelick3 have provided what we believe is direct evidence in support of this hypothesis. In these in vitro studies, stimulation of rat pancreatic acini with a supramaximally stimulating dose of cerulein resulted not only in activation of digestive enzyme zymogens but also acinar cell injury. Inhibition of trypsin activity in these experiments prevented ceruleininduced acinar cell injury, thus clearly showing that premature activation of digestive enzyme zymogens can lead to the acinar cell injury observed during cerulein-induced pancreatitis. However, as we have pointed out in several of our recent publications, we believe that only the ‘‘initial injury’’ to the gland during pancreatitis is caused by the premature activation of digestive enzyme zymogens. The ultimate severity of the disease is determined by events that occur subsequent to the initial acinar cell injury. The exact nature of these events is the subject of intense ongoing investigations. They probably involve a variety of factors including cytokines, chemokines, PAF, oxygenderived free radicals, apoptosis, and necrosis. We4 and others have recently shown that substance P acting via neurokinin (NK-1) receptors, chemokines interacting with CCR1 receptors, ICAM-1, PAF, tumor necrosis factor ␣, several different interleukins, as well as complement system play an important role in determining the severity of pancreatitis both clinically and in animal models. Certainly, this list will expand in the near future. There could be several reasons for the different findings in our study5 compared with those of Sandoval et al.6 dealing with the role of PAF during pancreatitis. Sandoval et al. have reported almost complete prevention of pancreatitis using a PAF receptor antagonist, whereas in our studies, in which PAF was neutralized by its hydrolysis with PAF-acetylhydolase, we found only partial but significant
September 1999
protection. The 2 studies differed in other important experimental details. Of note, a recent announcement from British Biotech indicates that their PAF-receptor antagonist Lexipafant was not effective against pancreatitis in a large multicenter clinical trial. In the opossum duct ligation model, we routinely observe morphological acinar cell injury/necrosis that is significantly more extensive than the 11% reported by Gukovskaya et al.7 We do not know the reason for these differences, but they are certainly not due to our inability to detect apoptosis in this model because neither we8 nor Gukovskaya et al.7 have found evidence of significant apoptosis after 7 days of duct ligation in opossums. Dr. Blackstone is correct in pointing out that PAF might regulate ICAM-1 expression and, as a result, the neutrophil sequestration in the pancreas that is observed during pancreatitis. We are in the process of studying such interactions. However, we do not believe that PAF and ICAM-1 are the only players in this game. Sandoval et al.,6 in the article referred to by Dr. Blackstone, state that ‘‘. . . [we] hypothesize that an initial pancreatic injury causes expression of PAF that mediates activation and infiltration of neutrophils in the tissues [during pancreatitis].’’ We basically agree with this hypothesis but would argue that the initial pancreatic injury referred to by Sandoval et al. is the result of premature activation of digestive enzyme zymogens within pancreatic acinar cells. ASHOK K. SALUJA, Ph.D. MICHAEL L. STEER, M.D. Beth Israel Deaconess Medical Center Harvard Medical School Boston, Massachusetts 1. Saluja AK, Donovan EA, Yamanaka K, et al. Caerulein-induced in vitro activation of trypsinogen in rat pancreatic acini is mediated by cathepsin B. Gastroenterology 1997;113:304–310. 2. Saluja A, Bhagat L, Lee H, et al. Role of calcium in CCK-induced trypsinogen activation and acinar cell injury. Am J Physiol 1998. 3. Grady T, Mah’Moud M, Otani T, et al. Zymogen proteolysis within the pancreatic acinar cell is associated with cellular injury. Am J Physiol 1998;275:G1010–G1017. 4. Saluja A, Steer M. Pathophysiology of pancreatitis: role of cytokines and other mediators. Digestion 1998;60:27–33. 5. Hofbauer B, Saluja A, Bhatia M, et al. Effect of recombinant platelet-activating factor acetylhydrolase on two models of experimental acute pancreatitis. Gastroenterology 1998;115:1238–1247. 6. Sandoval D, Gukovskaya A, Reavey P, et al. The role of neutrophils and platelet-activating factor in mediating experimental pancreatitis. Gastroenterology 1996;111:1081–1091. 7. Gukovskaya AS, Perkins P, Zaninvic V, et al. Mechanisms of cell death after pancreatic duct obstruction in opossum and rat. Gastroenterology 1996;110:875–884. 8. Kaiser A, Saluja A, Sengupta A, et al. Relationship between severity, necrosis and apoptosis in five models of experimental acute pancreatitis. Am J Physiol 1995;38:C1295–C1304.
CORRESPONDENCE 749
enteropathy are gluten dependent. Anticonnective tissue antibodies were first described in DH1 and subsequently found in celiac disease. It was suggested that reticulin or another connective tissue antigen may be the autoantigen in DH and celiac disease. Recently, tissue transglutaminase (TTG) was suggested to be the autoantigen in celiac disease.2 A very high incidence of tissue transglutaminase antibodies (TTA) was subsequently found in patients with celiac disease.3,4 We now report our findings on TTA in DH and the effect of gluten withdrawal on these antibodies. Seventy-two patients with DH and 18 controls (with other autoimmune bullous diseases, cicatricial pemphigoid, pemphigus, and linear IgA disease) were studied. DH was confirmed in all patients by the presence of IgA in the dermal papillae, and 67 had intestinal biopsy specimens. Thirty-seven of the patients had been on a strict gluten-free diet (GFD) for more than 2 years; 20 on a partial GFD, defined as patients knowingly consuming gluten-containing food but not more frequently than once a week; and 15 on a normal diet. Serum was screened for IgA antiendomysial antibody (AEA) at a dilution of 1/5 with umbilical cord as substrate. IgA TTA was screened for by an enzyme-linked immunosorbent assay (ELISA kit; Inova Diagnostics, San Diego, CA) using guinea pig liver TT antigen and goat anti-human IgA. Sample values were calculated as recommended by the manufacturer; a positive result was indicated by a unit value greater than 20. Appropriate positive and negative (no serum) controls were included. Figure 1 shows the titers of TTA measured in the patients with DH. Among the 15 patients consuming a normal diet, AEA was detected in 10 (67%) and TTA in 12 (75%). All 10 patients who had AEA were TTA positive, 2 had TTA alone, and 3 had neither antibody. Among the 20 patients on a partial GFD, AEA was present in 5 (25%) and TTA in 7 (35%). Again, there was a good correlation between the presence of AEA and TTA. In all 5 patients who had AEA, TTA was also present. Among the 37 patients on a strict GFD for at least 2 years, AEA was not present in any but TTA was present in 1 patient. One of the 18 control patients with bullous disease, who had cicatricial pemphigoid, had a positive TTA. Small intestinal biopsy specimens were obtained from 13 of the 15 patients on a normal diet. The 2 patients who declined to undergo biopsy both had TTA and AEA. Nine of the 13 specimens showed
Tissue Transglutaminase Antibodies in Dermatitis Herpetiformis Dear Sir: Dermatitis herpetiformis (DH) has a characteristic rash, and the hallmark of the disease is immunoglobulin (Ig) A deposits in the dermal papillae. Two thirds of patients have an enteropathy indistinguishable from celiac disease, and the remaining third have associated features of gluten sensitivity (increased intraepithelial lymphocyte [IEL] count and/or increase of ␥/⌬ T cells). Both the rash and the
Figure 1. TTA in patients with DH in relation to diet. Antibodies were measured using a specific ELISA. Results are expressed as optical density at 450 nm; values below 20 were considered negative.