Drug-triggered pemphigus in a predisposed woman

A 31-year-old woman with three pemphigus-prone antigens in her HLA haplotype (B7, DR4, DQw7) developed the disease soon after taking a pyrazolone derivative, viz. feprazone. The pemphigus lesions persisted despite withdrawal of the drug and worsened appreciably when she used ceftriaxone (a new cephalosporin with three sulphur atoms) for a bout of acute pharyngitis. Thiol groups formed from the metabolic breakdown of ceftriaxone are thought to have promoted acantholysis via a biochemical route. Genetic predisposition alone ('the soil') may be essential, though not per se sufficient for outbreak of pemphigus; the intervention of exogenous, heterogeneous factors ('the seed') often seems decisive in triggering full-blown disease.

Autoantibodies against a novel epithelial cadherin in pemphigus vulgaris, a disease of cell adhesion

Pemphigus vulgaris (PV) is a life-threatening skin disease in which autoantibodies against a keratinocyte cell surface 130 kd glycoprotein, PV antigen (PVA), cause loss of cell-cell adhesion, with resultant epidermal blisters. We used affinity-purified PV IgG to isolate cDNA, containing the entire coding sequence for PVA, from human keratinocyte expression libraries. Northern blot analysis indicated PV mRNA expression only in stratified squamous epithelia. The deduced amino acid sequence of PVA was unique but showed significant homology with members of the cadherin family of Ca(2+)-dependent cell adhesion molecules, most markedly to desmoglein I. These findings demonstrate that a novel epithelial cadherin is the target of autoantibodies in PV.

HLA class II antigens are associated with Japanese pemphigus patients

We investigated the HLA class II antigens in 30 Japanese cases of pemphigus, 17 cases of pemphigus vulgaris (PV) and 13 cases of pemphigus foliaceus (PF), by both serologic and restriction fragment length polymorphism (RFLP) analyses. We detected two major haplotypes susceptible to PV, i.e., DRw12-DQw7 and DRw6-DQw5. In contrast, DR2 was absent in PV. RFLP analyses showed that DRw6 PV patients had a disease-associated restriction fragment representing DQw5, the same association as that found in DRw6 Jewish PV patients. However, DRw12 Japanese PV patients had DQw7, whereas DR4 Jewish PV patients had DQw8. On the other hand, all 13 PF patients were serologically typed for DQw1, which could not be further subdivided into DQw5 by RFLP analyses. These results suggest that Japanese and Jewish PV patients may be immunogenetically closely related to each other, but Japanese PV patients appear to be immunogenetically different from Japanese PF patients.

Major histocompatibility complex haplotypes and class II genes in non-Jewish patients with pemphigus vulgaris

Previous studies demonstrated that HLA-DR4 was markedly increased among Ashkenazi Jewish patients with pemphigus vulgaris (PV), almost entirely as the common Jewish extended haplotype [HLA-B38, SC21, DR4, DQw8] or as the haplotype HLA-B35, SC31, DR4, DQw8, and that HLA-DR4, DQw8 was distributed among patients in a manner consistent with dominant expression of a class II (D-region or D-region-linked) susceptibility gene. In the present study of major histocompatibility complex (MHC) haplotypes in 25 non-Jewish PV patients, DR4, DQw8 was found in 12 of the patients and DRw6, DQw5 was found in 15. Only 3 patients had neither. Only 1 of the DR4, DQw8 haplotypes was [HLA-B38, SC21, DR4, DQw8] and 2 were HLA-B35, SC31, DR4, DQw8; most were the presumed fragments (SC31, DR4, DQw8) or (SC21, DR4, DQw8) or DR4, DQw8 with some other complotype. Of the patients with DRw6, DQw5, all were DRw14, DQw5, and 6 had a rare Caucasian haplotype, HLA-Bw55, SB45, DRw14, DQw5. Four of 6 of these were found in patients of Italian extraction, as was the 1 normal example. The non-Jewish patients were of more Southern European extraction than our controls. This suggests that there are two major MHC susceptibility alleles in American patients with PV. The more ancient apparently arose on a haplotype in the Jews, HLA-B38(35), SC21(SC31), DR4, DQw8, and spread to other populations largely as D-region segments. The other arose in or near Italy on the haplotype HLA-Bw55, SB45, DRw14, DQw5 and has also partially fragmented so that many patients carry only DRw14, DQw5. The available data do not permit the specific localization of either the DR4, DQw8- or the DRw14, DQw5-linked susceptibility genes.

HLA antigens and risk for development of pemphigus foliaceus (fogo selvagem) in endemic areas of Brazil

Endemic pemphigus foliaceus (EPF), is an autoimmune disease associated with production of IgG antibodies against epidermal antigens. We have tested 38 patients and 50 control subjects living in endemic areas to investigate whether HLA genes are associated with host factors that determine whether or not exposed individuals will develop this disease. A variant of HLA-DR1, an antigen common in Blacks (DRB1*0102), was found to be the main susceptibility factor (relative risk = 7.3, P less than 0.0002). Two amino acids, in positions 85 and 86 of DRB1, distinguish DRB1*0102 from DRB1*0101. These residues appear to be involved in the formation of a functional epitope that causes T cell recognition and determines disease susceptibility. Moreover, subjects having DQw2 did not develop the disease, while the frequency of DQw2 in controls was 22% (RR = 0.04, P less than 0.006). Thus HLA genes appear to play a crucial role in the response to an environmental factor which in this setting frequently leads to the development of autoimmune disease. An HLA-DQ allele, DQw2, appears to be associated with factors that prevent the development of the disease in exposed individuals.

Pemphigus in families

A family in which two sisters are affected by pemphigus is described. Literature research has revealed the presence of 25 families, comprising 53 patients, in which pemphigus existed in more than one member. The relationships between those affected were mainly parent-child or sibling-sibling. Pemphigus was found to be associated with specific HLA antigens: A26, Bw38, DRw4, and additionally occurred with a higher frequency in certain ethnic groups. The variety of etiologic factors in the pathogenesis of pemphigus is discussed and the significance of a genetic role elucidated.

Hailey-Hailey disease: a widespread abnormality of cell adhesion

Suction has been used to investigate cell adhesion in clinically normal skin in Hailey-Hailey disease. We have demonstrated that there is a widespread subclinical abnormality in keratinocyte adhesion in this disease. There may be a synthesis of functionally deficient adhesion junctions, increased breakdown of adhesion junctions or abnormalities in other adhesion proteins in the epidermis in Hailey-Hailey disease. The findings contrast with those in Darier's disease in which abnormal cell adhesion was only demonstrable in clinically involved skin.

[Polymorphisms of HLA class II antigens in 33 Japanese pemphigus patients]

The HLA class II antigens in 33 Japanese pemphigus patients were investigated by both serologic and restriction fragment length polymorphism (RFLP) analyses: 17 cases of pemphigus vulgaris (PV), 13 cases of pemphigus foliaceus (PF), 3 cases of unclassified pemphigus. In serologic typing, DR2 was absent in PV. DR5, DRw6, DRw12, and DRw52 were positively associated with PV. DQw1 was positively associated with PF. RFLP analyses showed that DRw6 PV patients had a disease-associated restriction fragment representing DQw5, the same association as that found in DRw6 Jewish PV patients. On the other hand, all 13 PF patients were serologically typed for DQw1, which could not be further subdivided into DQw5 by RFLP analyses. These results suggest that Japanese and Jewish PV patients may be immunogenetically closely related to each other, but Japanese PV patients appear to be immunogenetically different from Japanese PF patients.

PCR-SSO typing in HLA-disease association studies

Associations between a large number of diseases and markers within the major histocompatibility complex (MHC) have been described. In particular, susceptibility to several autoimmune disorders, including type I diabetes mellitus and rheumatoid arthritis, is linked to genes within the MHC and strong population associations are demonstrable between certain HLA class II alleles and these conditions. Genetic mapping of HLA susceptibility loci has traditionally relied on the use of phenotypic markers defined by alloantisera, cellular typing reagents and biochemical analysis of histocompatibility antigens. Polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) typing combines the ability to define the finest of HLA specificities, by analysis of the corresponding DNA sequences, with the possibility of study large populations of normal and affected individuals. The applications of this technology to characterizing precisely the MHC loci associated with susceptibility to autoimmune diseases such as rheumatoid arthritis, type I diabetes mellitus, coeliac disease and pemphigus vulgaris are reviewed here.

Complement allotypes in Japanese patients with pemphigus and bullous pemphigoid

The allotypes of C6, C7, factor B (BF) and factor I (IF) of the human complement system were studied in 11 Japanese patients with pemphigus (5 with pemphigus vulgaris and 6 with pemphigus foliaceus) and 17 with bullous pemphigoid (BP) to investigate the genetic background of these diseases. The allotypes were detected by using isoelectric focusing and immunoblotting. The frequency for IF*A allele in the pemphigus patients was significantly higher (p = 0.009) than that in healthy controls (n = 60). A significant association of IF A allotype with pemphigus was also observed (p = 0.027), with a relative risk of 6.3. There was no association between the C6, C7, BF or IF allotypes and BP. These data suggest that IF A allotype may be an etiological genetic factor in the development of pemphigus.

Desmoglein shows extensive homology to the cadherin family of cell adhesion molecules

Desmoglein is a major adhesive component of the desmosome. It is also at least one of the antigenic targets of pathogenic antibodies circulating in the sera of patients with the blistering disease Pemphigus foliaceus. To examine the molecular basis of desmosomal adhesion and to further our understanding of its disruption in various bullous disorders we have cloned cDNAs encoding four of the extracellular domains of desmoglein. The predicted amino acid sequence of these clones shows extensive homology with the cadherin class of calcium-dependent cell adhesion molecules. Desmoglein represents a novel subtype of this family.

Major histocompatibility complex haplotype studies in Ashkenazi Jewish patients with pemphigus vulgaris

Of 26 Ashkenazi Jewish patients with pemphigus vulgaris, 24 (92.3%) carried the major histocompatibility complex (MHC) class II alleles HLA-DR4, DQw3, of which all were of the subtype DR4, DQw8. From studies of the patients and their families, haplotypes were defined. It was found that, of the patients who carried HLA-DR4, DQw8, 75% carried one or the other (and in one case, both) of two haplotypes [HLA-B38, SC21, DR4] or HLA-B35, SC31, DR4. The former is a known extended haplotype among normal Jews, with a frequency of 0.102, and the latter may also be an extended haplotype in this ethnic group, with a frequency of 0.017 among normal haplotypes from Jews. Of the remaining DR4-positive patients, all but one had a presumed D-region segment (defined as SC21, DR4, DQw8 or SC31, DR4, DQw8 with variable HLA-B) of these haplotypes. Only one patient had DR4, DQw8 without any other markers of the extended haplotypes. The number of homozygotes and heterozygotes for DR4, DQw8 was consistent with dominant but not recessive (P less than 0.01) inheritance of a class II or a class II-linked susceptibility gene for the disease. Since the disease is entirely attributable to the presence of an antibody to an intraepidermal intercellular cement substance, it is likely that the class II susceptibility gene (on [HLA-B38, SC21, DR4, DQw8], HLA-B35, SC31, DR4, DQw8, or their segments, in Jewish patients) controls the production of the antibody as a dominantly expressed immune response gene.

[Organ culture of skins from patients with benign familial chronic pemphigus]

Skin explants from 2 lesional skins and 3 normal appearing skins of patients with benign familial chronic pemphigus (BFCP) were organ cultured with and without various reagents. In the culture of involved skin, acantholysis which was also observed prior to culturing and which strengthened during the 72 hr culture, was not suppressed when betamethasone or retinol acetate was added to the medium. In the culture of un-involved skin explants with medium only, acantholysis was induced 24-48 hr after initiation of culture, and became apparent after 72 hr. Such experimentally induced acantholysis was almost completely suppressed by the addition of betamethasone, but not the addition of retinol acetate. These findings suggest that steroid has the efficacy to reduce blistering in BFCP, and that this in vitro model is useful for clarifying the pathogenesis as well as for discovering new drugs for the treatment of this disease.

Complotypes in pemphigus vulgaris: differences between Jewish and non-Jewish patients

Haplotypes of alleles of the major histocompatibility complex (MHC) complement genes BF, C2, C4A, and C4B are inherited as single highly polymorphic genetic units called complotypes. There are about a dozen complotypes with frequencies above about 0.01 in Caucasians. In the blistering disease pemphigus vulgaris, the complotypes SC21 and SB45 were found to be markedly elevated in patients compared with general Caucasian controls. The SC21 increase was in Ashkenazi Jewish patients exclusively (relative risk = 17 in that population), whereas SB45 was found solely in non-Jewish Caucasians (specific population relative risk = 57). Although these are unusually high relative risks, it is most unlikely that these complotypes represent susceptibility genes for pemphigus vulgaris. Rather, it is probable that they mark extended major histocompatibility complex haplotypes with fixed DNA so that independent examples in the population have the same alleles. It is likely that it is the class II genes on these haplotypes that confer susceptibility.

Familial pemphigus vulgaris

Familial pemphigus vulgaris was found in a Jewish woman and her son who developed the disease within a period of 18 months from one another. HLA typing was performed in the mother and son as well as in the unaffected father and sister. Examination of the HLA antigens in this family indicates that there may be different variants of DR4, DQw3 and that one of them carried by the mother and son as part of the haplotype A30, B18, DR4, DQw3 is associated with pemphigus vulgaris. Our findings are in favor of the concept that particular polymorphic residues of class II major histocompatibility molecules are correlated with disease susceptibility.

Benign familial pemphigus complicated by herpes simplex virus

Herpes simplex should be recognized as a precipitating factor, a secondary invader, or an imitator of chronic benign familial pemphigus. Results of Tzanck smear and viral culture can confirm the presence of the pathogen so that acyclovir therapy can be instituted.

Contact allergies in patients with familial benign chronic pemphigus (Hailey-Hailey disease)

To determine whether patients with familial benign chronic pemphigus have an increased risk for the development of contact allergies to topical therapy, we performed epicutaneous tests in 15 patients with this disease. Nine had positive patch test reactions of which seven were allergic to compounds used in local treatments. Allergic reactions in more than one patient were seen to neomycin sulfate (three patients), bacitracin (two), and hydrocortisone-17-butyrate and betamethasone-17-valerate (two). Although no comparable control group was similarly studied, the frequency of sensitization appears to be increased in patients with familial benign chronic pemphigus.

Specific HLA-DQB and HLA-DRB1 alleles confer susceptibility to pemphigus vulgaris

The autoimmune dermatologic disease pemphigus vulgaris (PV) is associated with the serotypes HLA-DR4 and HLA-DRw6. Based on nucleotide sequence and oligonucleotide probe analysis of enzymatically amplified DNA encoding HLA-DR beta chain (HLA-DRB) and HLA-DQ beta chain (HLA-DQB; henceforth HLA is omitted from designations), we showed previously that the DR4 susceptibility was associated with the Dw10 DRB1 allele [encoding the mixed lymphocyte culture (MLC)-defined Dw10 specificity]. The DRw6 susceptibility similarly was shown to be associated with a rare DQB allele (DQB1.3), which differed from another nonsusceptible allele by only a valine-to-aspartic acid substitution at position 57. Given the linkage disequilibrium that characterizes HLA haplotypes, it is difficult to assign disease susceptibility to a specific locus rather than to a closely linked gene(s) on the same haplotype. To address this problem, we have analyzed all of the polymorphic loci of the class II HLA region (DRB1, DRB3, DQA, DQB, and DPB) on the DRw6 haplotypes in patients and controls. In 22 PV patients, 4 different DRw6 haplotypes were found that encode the same DQ beta chain (DQB1.3) but contained silent nucleotide differences at the DQB locus as well as coding sequence differences in the DQA and DRB loci. These results, obtained by using a method for allele-specific polymerase chain reaction amplification, strongly support the hypothesis that the allele DQB1.3 confers susceptibility. This DQB allele is correlated with the MLC-defined Dw9 specificity and is associated with two different DRB1 alleles (the common "6A" associated with DRw13 and the rare "6B" associated with DRw14). Since 86% (19 of 22) of DRw6+ patients contain the DQB1.3 allele (vs. 3% of controls), whereas 64% (14 of 22) contain the DRB1 allele 6B (vs. 6% of the controls), we conclude that most of the DRw6 susceptibility to PV can be accounted for by the DQ beta chain.

Are HLA class II genes controlling susceptibility and resistance to Brazilian pemphigus foliaceus (fogo selvagem)?

In order to investigate the possible association between Brazilian pemphigus foliaceus and HLA, we studied 48 patients and 74 matched controls, all Brazilian Caucasoids, for HLA-A,B,C; DR1 to DRw8 and DQw1 to DQw3. The frequencies of DR1, DR4 and B16 were significantly increased, while DR7 was significantly decreased among the patients. Furthermore DQw2, likewise the DR specificities associated with it - DR3 and DR7 - never occurred among the patients in the absence of the susceptibility markers DR1, DQw1 or DR4, DQw3. Acting on these findings, we suggest that at least two MHC-class II genes are involved in the pathogenesis of Brazilian pemphigus foliaceus: at least one gene, associated to DR1,DQw1 and to DR4,DQw3, confers susceptibility and at least one gene, associated to DR7,DQw2 and DR3,DQw2, confers resistance. The susceptibility gene(s) seem(s) to be epistatic to or dominant over (if allelic) the resistance gene(s). Both are dominant over other alleles at their locus (or loci).