Characterization of mucosal antibodies in recurrent aphthous ulceration and Behcet's syndrome

Mucosal disease series. Number VI. Recurrent aphthous stomatitis

Recurrent aphthous stomatitis (RAS; aphthae; canker sores) is a common condition which is characterized by multiple recurrent small, round or ovoid ulcers with circumscribed margins, erythematous haloes, and yellow or grey floors typically presenting first in childhood or adolescence. RAS occurs worldwide although it appears most common in the developed world. The aetiology of RAS is not entirely clear. Despite many studies trying to identify a causal microorganism, RAS does not appear to be infectious. A genetic predisposition is present, as shown by strong associations with genotypes of IL-1beta; IL-6 in RAS patients, and a positive family history in about one-third of patients with RAS. Haematinic deficiency is found in up to 20% of patients. Cessation of smoking may precipitate or exacerbate RAS in some cases. Ulcers similar to RAS may be seen in human immunodeficiency virus disease and some other immune defects, and drugs, especially non-steroidal anti-inflammatory drugs and nicorandil may produce lesions clinically similar to RAS. Topical corticosteroids can often control RAS. However, the treatment of RAS remains unsatisfactory, as most therapies only reduce the severity of the ulceration and do not stop recurrence.

Cloning and sequencing of BeS-1 gene encoding the immunogenic antigen of Streptococcus sanguis KTH-1 isolated from the patients with Behçet's disease

In order to analyze the immunopathologic mechanisms of Behçet's disease, the gene (bes-1) encoding a streptococcal antigen correlated with the disease was cloned and sequenced, and protein produced by this clone was identified by Western immunoblotting using serum antibody from the patient. Cellular DNA of Streptococcus (S.) sanguis serotype KTH-1 (uncommon serotype 1, strain 113-20) from the patient was extracted and digested with EcoRI. The digested fragments were cloned into the cloning vector lambda gt11, and then the resulting DNA library was immunoscreened using the patient's serum antibody to serotype KTH-1. The immunopositive clone of the 1.5 kbp fragment was subcloned into pUC 118 plasmid (pU8BeS1-1) and sequenced. The sequence showed that the 3'-terminal half side region of this insert contained 962bp of open-reading frame (ORF) discontinued at the EcoRI restriction site, and the stop codon was not found. The nucleotide sequence of the remaining additional 3'-terminal region of this gene encoding whole BES-1 was determined by genome walking. The whole ORF of bes-1 consisted of 849 amino acid residues with a calculated molecular mass of 95 kDa. The residues in a portion of the amino acid sequence showed a 60% correspondence to those of the human intraocular peptide Brn-3b.

Preliminary evidence for an association of Epstein-Barr virus with pre-ulcerative oral lesions in patients with recurrent aphthous ulcers or Behçet's disease

In this study we used the polymerase chain reaction (PCR), slot blot and Southern blot hybridization, direct sequencing and in situ hybridization (ISH) to show the possible presence of EBV-DNA in pre-ulcerative oral aphthous lesions of patients with recurrent aphthous ulcers (RAU) or Behçet's disease (BD). For this purpose, formalin-fixed biopsy specimens were obtained from 13 pre-ulcerative oral aphthous lesions of nine RAU and four BD patients. Five specimens of normal oral mucosa (NOM) from five normal control subjects and 10 specimens of oral erosive or ulcerative lesions from 10 patients with erosive lichen planus (ELP) were also included. EBV-DNA was detected by PCR in 5 of the 13 (38.5%) pre-ulcerative oral aphthous lesions, two from RAU patients and three from BD patients. However, no EBV-DNA was demonstrated in five NOM specimens from normal control subjects and in 10 specimens of oral lesions from ELP patients. EBV-DNA was also demonstrated in patients' peripheral blood lymphocytes and/or plasma, suggesting that the lymphocytes may be the reservoir of latent EBV infection and there is EBV shedding in the plasma. EBV-DNA was detected by ISH in only one PCR-positive case; the reaction product was found to deposit on the nuclei of some of the epithelial cells and lymphocytes. By immunohistochemistry, expression of Epstein-Barr nuclear antigen and EBV/C3d receptors was also noted in some of the epithelial cells and lymphocytes in this ISH-positive case. Therefore, we suggest that the epithelial cells of pre-ulcerative oral aphthous lesions may be infected by EBV through EBV-infected lymphocytes; also, the cytotoxic T lymphocyte-induced lysis of the EBV-infected epithelial cells, but not the virus-induced cytolysis, may be the main mechanism causing oral ulcer formation. Our data provide preliminary evidence for an association of EBV with pre-ulcerative oral aphthous lesions in RAU and BD patients.

Human cytomegalovirus as a potential etiologic agent in recurrent aphthous ulcers and Behçet's disease

In a preliminary study on anti-human cytomegalovirus (HCMV) antibody (Ab) by ELISA, the serum anti-HCMV/IgG Ab concentrations in 22 patients with recurrent aphthous ulcers (RAU) in the remission stage were found to be significantly higher than in 22 control subjects (121 +/- 42 vs 100 +/- 27, P < 0.05) and in 39 patients with RAU in the active stage (121 +/- 42 vs 88 +/- 45, P < 0.01). Therefore, the potential of HCMV as an etiologic agent in RAU was proposed and studies using the polymerase chain reaction (PCR) and in situ hybridization (ISH) have been performed to investigate the possible presence of HCMV DNA in pre-ulcerative oral aphthous lesions in patients with RAU or Behçet's disease (BD) of the mucocutaneous type. For this purpose, formalin-fixed biopsy specimens were obtained from 13 pre-ulcerative oral aphthous lesions, 2 samples of normal oral mucosa and 1 ileal mucosal lesion from 9 RAU patients and 4 BD patients. Five specimens of normal oral mucosa from 5 normal control subjects and 12 specimens of oral erosive or ulcerative lesions from 12 patients with erosive lichen planus (ELP) were also included. By PCR, HCMV DNA was detected in 5 of the 13 (38.5%) pre-ulcerative oral aphthous lesions, 3 from RAU patients and 2 from BD patients. The ileal mucosa specimen was also HCMV DNA-positive, whereas HCMV DNA was not demonstrated in any of the 7 specimens of normal oral mucosa from RAU patients and normal control subjects; 12 specimens of oral lesions from ELP patients were similarly negative. ISH did not detect HCMV DNA in any of the biopsy specimens from RAU patients and control subjects. Our findings suggest that HCMV may be an etiologic agent in some cases of RAU and BD.

Recognition of a unique peptide epitope of the mycobacterial and human heat shock protein 65-60 antigen by T cells of patients with recurrent oral ulcers

T cell epitopes of the 65-kD heat shock protein (hsp) were investigated in patients with recurrent oral ulcers (ROU). Peripheral blood mononuclear cells were stimulated with overlapping synthetic peptide (15ers), derived from the sequence of the 65-kD hsp of Mycobacterium tuberculosis. Specific lymphoproliferative responses were stimulated only with peptide 91-105 in ROU, compared with healthy or disease controls (P < 0.01). This was confirmed by studying 760 short term cell lines generated with the 65-kD hsp and then stimulated with the peptides. The frequency of short term cells lines responding to peptide 91-105 in ROU was significantly greater than in healthy (P < 0.0001) or disease controls (P < 0.01). A comparative investigation with the homologous human 60-kD hsp peptide 116-130 also showed significantly greater lymphoproliferative responses in ROU than in healthy (P < 0.01) or disease controls (P < 0.001). The potential involvement of the T cell epitope 91-105 in the pathogenesis of ROU is supported by finding a significant increase in the lymphoproliferative responses stimulated with peptide 91-105 during the stage of ulceration, compared with remission in 9/11 patients studied sequentially (P < 0.05). The results suggest that oral ulceration might be initiated by the microbial hsp peptide 91-105 stimulating the mucosal Langerhans cells, which may generate autoreactive T cell clones primed to the homologous peptide 116-130.

Humoral responses and cross-reactivity to viridans streptococci in recurrent aphthous ulceration

It has been proposed that recurrent aphthous ulceration (RAU) is caused by hypersensitivity to oral streptococci. This hypothesis is based on reports that RAU patients have increased levels of circulating IgG antibodies against oral streptococci, and that rabbit antisera prepared against oral streptococci are cross-reactive with oral mucosa. Using indirect immunofluorescence, we have investigated both of these reported phenomena. End-point titers of serum antibodies against three different strains of oral streptococci were assayed from nine RAU subjects with active ulcers and compared with those of nine control subjects. Titers ranged from 1:2 to 1:64 in both groups and do not appear to have any clinical or immunopathogenic significance. Cross-reactivity was studied using hyperimmune rabbit antisera raised against five different strains of oral streptococci. Homologous bacterial titers ranged from 1:1024 to 1:8192, but none of these anti-streptococcal sera produced heterologous titers greater than 1:32 with oral mucosa. This apparent low level of cross-reactivity with oral mucosal antigens appears to be non-specific and clinically insignificant. In previous reports, we have used both leucocyte migration and lymphocyte blast transformation to study cell-mediated immunity to viridans streptococci in RAU (Gadol et al., 1985; Greenspan et al., 1985). None of our results supports an immunopathogenic role for oral streptococci in RAU.

Antibodies to oral mucosa in patients with ocular Behcet's disease

A method is reported for the identification of cytoplasmic antibodies in patients with Behcet's disease and uveitis. The assay appears positive in at least 80% of patients in an American population with definite or probable Behcet's disease and 60% of patients from a Turkish population with definite Behcet's disease, with a false-positive rate of 6.5% among non-Behcet's ocular inflammatory disorders with vasculitis. When refined, this test may prove useful to the ophthalmologist in selecting out those patients with Behcet's disease from the larger group of patients with uveitis for whom no systemic etiology is identified.

Lymphocyte function in recurrent aphthous ulceration

Lymphocyte blast transformation responses to mitogens and to streptococcal, adenovirus Type 1, and oral mucosal antigens were studied in 32 patients with recurrent aphthous ulceration (RAU) and matched control subjects. RAU patients showed significantly depressed (p less than 0.05) responses to mitogens in comparison with matched controls, but there was no significant difference between patients and controls in response to any of the antigens tested. These results indicate that neither cell-mediated hypersensitivity to streptococcal or viral antigens nor cross-reactivity between oral mucosal and streptococcal antigens are likely to play a role in the pathogenesis of RAU. Rather, the data support the hypothesis of an imbalance or defect in immune cell subpopulations.

Immunologic disorders of the skin and mucous membranes

This article provides a practical approach to those dermatologic disorders in which an immunologic mechanism is involved in the pathophysiology. There is a brief discussion of evaluation and management for many of these disorders.

Lytic effects of serum and mononuclear leukocytes on oral epithelial cells in recurrent aphthous stomatitis

A radioisotope-release assay, utilizing 51Cr-labeled epithelial cells derived from non-keratinizing oral mucosa, was developed to investigate in vitro cytolytic reactions correlating with recurrent aphthous stomatitis (RAS). The cytolytic effects of sera and mononuclear leukocytes from patients in the early stage of ulceration were compared with those from matched RAS-negative control subjects. RAS sera induced significantly more cytolysis than did matched control sera. Heating the RAS or control sera for 30 min at 56 degrees C abrogated their cytotoxic activity. RAS mononuclear leukocytes, like their matched controls, showed no significant direct cytotoxicity. Heat-inactivated RAS or control sera acting in concert with RAS or control mononuclear leukocytes showed no consistent cytolytic effects. However, the heat-inactivated sera of some RAS patients, when combined with autologous mononuclear leukocytes, induced significantly more cytolysis than did either component acting alone. Thus heat-labile humoral factors and, in some cases, mononuclear leukocytes acting in concert with heat-stable serum factors are implicated in RAS-associated in vitro cytolytic reactions. These findings suggest that the effector mechanisms of such reactions include both complement-mediated and antibody-dependent cell-mediated cytotoxicity.

Microbial pathogenicity in oral soft tissue diseases

Recent work implicating microbial factors in the pathogenesis of several oral soft tissue diseases is discussed. These conditions include recurrent aphthous ulceration, oral cancer, Sjogren's syndrome, and the oral lesions of AIDS (the acquired immune deficiency syndrome). This paper reviews some recent work on these topics, with emphasis on investigations in our laboratory.

Behçet's syndrome: immune regulation, circulating immune complexes, neutrophil migration, and colchicine therapy

Immune regulatory dysfunction, circulating immune complexes (CIC), and polymorphonuclear (PMN) cell migration were investigated in patients with Behçet's syndrome. Six patients meeting rigorous clinical criteria were evaluated. Only one patient showed evidence of immune regulatory dysfunction (increased T4/T8 ratio). Although C1q binding and Raji cell assays for CIC yielded positive results in only one of five patients, all five patients had in vivo "histamine trap test" evidence of CIC (all controls had normal results). Sera from all Behçet's syndrome patients increased migration of neutrophils to zymosan-activated serum. Colchicine therapy abolished the enhancing effect of the patient's sera on movement of PMN cells from patients and controls. An immune complex-mediated injury that is followed by an excessive accumulation of PMN cells may lead to the cutaneous lesions and other lesions in Behçet's syndrome. Further evaluation of colchicine therapy is warranted on the basis of these studies.

The rôle of immunological reactions in apical cyst formation and the fate of epithelial cells after root canal therapy: a theory

Activation of the epithelial cell rests of Malassez by various means, results in proliferation of these cells and formation of apical periodontal cysts. Several theories for the genesis of apical periodontal cysts have been suggested which are not satisfactory. Available evidence indicates that development and destruction of these lesions are mediated by immunological reactions.

Immunogenetic markers and immune response in patients with recurrent oral ulceration

20 patients, aged 20 to 72 years (mean 36.5 years), 14 with recurrent (RAS) and 6 with recurrent cicatrizing (RCAS) aphthous stomatitis were studied. 3 patients (15%) had the HLA locus A11 antigen, whose frequency in the Finnish population is 8%. 5 patients (25%) had B12, which occurs in 15% of the normal population. Results of routine serological tests were normal. All had normal serum levels of IgG, IgM, IgA and complements C3 and C4. 4 patients, 2 with RAS and 2 with RCAS, had raised serum IgE. Precipitating antibodies against milk protein were detected in 2 patients and against gluten in 1. In 4 patients, tests for immediate allergy were positive. 5 patients had antibodies to double-stranded DNA. Delayed hypersensitivity reactions were normal, and the PHA stimulation of lymphocytes elicited normal T-cell responses in all patients except one with RCAS. In this patient, there was a striking parallelism between an increase in PHA-reactive lymphocytes and clinical improvement. The serum of this patient contained a binder for 125I-labelled PHA, a binder not consistently detected in the other patients with ROU. Lymphocyte dysfunction may play a rôle in ROU. Of the 16 biopsy specimens of aphthous tissue studied by direct immunofluorescence for IgG, IgM, IgA, fibrinogen and C3, 15 specimens contained deposits of C3 in and along mucosal vessels, whereas among the 15 controls only 1 specimen of erosive lichen planus showed deposits of C3 along capillary walls. Immune complexes precipitating in capillary walls appear to be a common feature of ROU.

Functional aberration of T cell subsets in patients with Behçet's disease

Abnormalities of concanavalin A-induced suppressor activity and autologous mixed lymphocyte reaction (which is part of the regulatory role of T cells on lymphocyte functions) were observed in patients with preactive Behçet's disease. However, both the functions returned to normal when the patients entered an active or inactive phase of disease. Thus, a diminution of suppressor function appears to be necessary for the initiation or potentiation of autoimmune and/or inflammatory abnormalities in Behçet's disease. Results of studies of T cell subsets and their functional analysis in patients with preactive Behçet's disease provide further evidence in support of this hypothesis.

Lytic effect of cytotoxic lymphocytes on oral epithelial cells in Behçet's disease

The effect of blood lymphocytes on syngeneic oral epithelial cells was studied in twelve patients with Behçet's disease (BD) and twenty-one patients with recurrent aphthous ulcers (RAU). The control group consisted of twenty-five patients with non-aphthous skin disease and eight healthy individuals. Primary cell lines obtained from oral mucosa by suction blistering and subsequent enzymatic dissociation were used as target cells. Using a modified 51chromium release macro-assay, a significant lytic effect due to antibody-independent lymphocytotoxicity could be demonstrated in patients with BD, but no significant lysis of target cells was found in the RAU patients compared with the control group. These results provide further evidence that antibody-independent lymphocytotoxicity may play an important role in oral ulceration in BD.

Behçet's disease

Behçet's disease is characterized by three primary components: iridocyclitis (historically with hypopyon), aphthous lesions in the mouth, and ulceration of the genitalia. Erythema nodosum, arthropathy and thrombophlebitis often accompany these manifestations, but the ocular symptoms may be the most important and serious manifestations of the disease. Central nervous system involvement, most often due to necrotizing vasculitis, may be the most protean manifestation of the disease, leading to death. The frequency of ocular manifestations is 70-85% in patients with the disease; the underlying disease mechanism in all organ systems is an occlusive vasculitis. Although the most common ocular symptom is that of anterior uveitis, often with hypopyon as a very late sign, the presence of necrotizing retinal vascular lesions is well known and often obscured by the severity of the anterior reaction. Definitions, incidence, clinical characteristics, differential diagnosis, and management of Behçet's ocular disease are discussed, as are the interrelationships of the different organ manifestations. The ophthalmologist should be familiar with the full spectrum of disease presentation since he or she may be the first physician to encounter the Behçet's patient.

Enhancement of granulocyte chemotaxis in Behcet's disease

The humoral and cellular immune status, the cutaneous pathergy, PMNL in vitro function tests as well as clinical and general laboratory examination were performed and evaluated on ten patients suffering from Behcet's disease (BD) and ten other patients with benign recurrent aphthosis (RA). The same set of in vitro tests (except PMNL exposure to solutions of copper sulfate or DDT) was carried out on a control group consisting of more than 100 healthy male and female individuals of various ages. Apart from general signs of inflammatory activity (leukocytosis, elevation of ESR, increased IgG serum levels), cutaneous pathergy to mild local highly injuries and marked enhancement of PMNL chemotaxis proved to be highly significant symptoms in acute phases of BD in contrast to benign RA. Both symptoms, in particular the hyperchemotaxis of PMNL, can be regarded as valuable diagnostic means in the early detection of beginning or atypical BD.

Treatment of Behcet's syndrome with levamisole

The clinical response to levamisole in 11 patients with complete Behcet's syndrome was reviewed. Nine patients responded, 3 completely and 6 partially, with reduction in the number and severity of buccal and genital lesions. In 3 patients each, ocular inflammation and gastrointestinal involvement responded to levamisole, and in 1 patient neurologic status improved. Levamisole was purposely discontinued in 3 patients to assess its true role in disease control. Each patient experienced a flare. Reintroduction of therapy controlled the flare in all cases, although 1 patient subsequently relapsed while continuing therapy. Two patients failed to respond. Side effects necessitated permanent discontinuation of the drug in 2 respondent patients, but in no case did neutropenia or agranulocytosis develop. These preliminary results suggest that levamisole may be useful in the therapy of the various manifestations of Behcet's syndrome and that a controlled prospective study is indicated.

Quantitative distribution of inflammatory cells in recurrent aphthous stomatitis

Histologic quantitation of leukocytes in biopsies of recurrent aphthous ulcers revealed at least two morphologically-distinct inflammatory infiltrates. Lymphocytes were found consistently in pre-ulcerative lesions and in the expanding margins of the developing ulcer. In contrast, polymorphonuclear leukocytes predominated only in areas of frank ulceration.

Behçet's syndrome: unusual multisystem involvement and immune complexes

A case of-Behçet's syndrome is described in which, in addition to the usual features of the condition, there was evidence of renal, gastric and cardiac involvement. Neurological involvement presented as hemisphere, transient ischaemic episodes. Immune complexes were detected and the patient responded promptly to prednisolone.

Immunological aspects of recurrent oral ulceration and Behçet's syndrome

Immunological factors play in recurrent oral ulceration (ROU) and Behçet's syndrome (BS) but these cannot be distinguished by means of antibodies and cell-mediated immune responses to oral mucosal antigens. However, HLA markers seem to differentiate ROU from BS. Immune complexes have now been found in about 55% of patients with BS and fewer patients with ROU, so that the transition from the focal ROU to the multifocal BS might be mediated by immune complexes. Immunopathological studies have shown that a vasculitis is the essential lesion in BS and this might be secondary to immune complexes inducing complement activation and damage. It is not clear at present whether the increased levels of C9 and C-reactive protein are a manifestation of acute phase reactants. C9 could be involved in complement dependent lysis and C-reactive protein in modulating the cell-mediated immune responses by its effect on T lymphocytes. It seems that at least two types of damaging immune mechanisms have been identified; cell-mediated and immune complex induced reactions and these might account for the association between ROU and BS.

Double-blind study of levamisole therapy in recurrent aphthous stomatitis

Forty-eight patients with diagnosed recurrent aphthous stomatitis participated in a randomized double-blind study of levamisole therapy. Each patient's response to treatment was determined by the following criteria: (1) days between attacks, (2) duration of lesions, (3) patient's self-evaluation of pain, (4) investigator's clinical evaluation of patient's subjective treatment response. Statistical analysis of the levamisole and placebo groups of criteria 1 and 2 above revealed no significant difference. In contrast to the above findings, analysis of the investigator's recordings of patient's subjective treatment response showed that 26% of the levamisole patients experienced marked or moderate improvement. None of the placebo patients were recorded as having experienced the same degree of benefit. Fourteen of 15 patients who complained of side effects were taking levamisole. The most common side effects were dysgeusia and hyperosmia.

Possibility of a viral etiology in recurrent aphthous ulcers and Behçet's syndrome

The clinical signs, laboratory data, and histological features of recurrent aphthous ulcers (RAU) and Behçet's syndrome suggest a viral etiology. In fact, there are reports of adenovirus isolations in herpetiform oral ulcers and on the isolation of a filterable agent in sporadic cases of Behçet's syndrome. However, isolation studies on the major and minor aphthous ulcers and more recent studies on Behçet's syndrome have been negative. A review of the literature on the role of viruses and autoimmunity in RAU and Behçet's syndrome is presented. Biopsy specimens of ulcerative lesions were grown in vitro for up to 300 days. Those cultures, along with leukocytes and body fluids, were examined by a variety of techniques for the presence of virus or viral antigens. Although a persistent or latent virus was not detected, these negative studies cannot exclude a viral etiology. In fact, the hypothesis of an infectious and viral etiology is still reasonable.

Effect of levamisole on the incidence and prevalence of recurrent aphthous stomatitis. A double-blind clinical trial

Twenty patients with severe recurrent aphthous stomatitis were treated with a new drug, levamisole, to determine its effects upon the incidence and prevalence of recurrent aphthous stomatitis. The trial, conducted in a non-crossover, double-blind fashion, did not demonstrate any statistically significant differences when levamisole and placebo groups were compared over time either in the number of ulcers, number of ulcer-days, mean duration of ulcers, or mean number of ulcers per day. Positive subjective results were experienced by the 10 patients receiving levamisole but these were not of sufficient magnitude to affect group mean differences.

Betamethasone-17-benzoate in the treatment of recurrent aphthous ulcers

A double-blind study of the effectiveness of betamethasone-17-benzoate in the treatment of recurrent aphothous ulcers (RAU) was concucted. The drug was found to be effective in reducing symptoms and shortening healing time but not in preventing recurrences. Evaluation of the medical histories and laboratory studies suggests that multiple factors may be involved in the etiology of RAU, as reported by others.

Aphthous ulcer--a treatment complication. Report of a case

Multiple theories of the cause and treatment of aphthous ulcers are described in the medical and dental literature. A case is reported in which there were posttreatment sequelae from the application of a sillver-nitrate stick (pencil) to an aphthous ulcer on the tongue. Compications subsequent to the use of silver nitrate may contraindicate the use of this agent in its highly concentrated form on the mucous membranes of the mouth.

A genetic study of Behçet disease in Israel

The frequency of HLA-B5 in 24 Israeli Behçet disease (BD) patients from various subpopulations was significantly greater than in 615 control individuals (P less than 0.003). The relative risk for a B5 carrier to develop BD was calculated to be 5.0. Six patients were offspring of consanguineous marriages, which is not unexpected in the populations studied. Five of the patients had only one HLA-B antigen, which in four cases was B5. Two of the latter were B5 homozygotes, indicating a possible greater susceptibility. This study confirms the reported association between BD and HLA-B5 in a populationnot previously investigated. Furthermore, these data support the suggestion that B5 is associated with BD in populations deriving from the Mediterranean Basin, the Middle East and Far East.

Recurrent aphthous stomatitis: clinical characteristics and evidence for an immunopathogenesis

Recurrent aphthous stomatitis is one of the most common diseases affecting the oral mucosa, and one of its variants is the most painful affliction of the oral mucosa. The lesions of recurrent aphthous stomatitis can be manifested as part of a broad spectrum of clinical disease ranging from the common minor aphthous ulcers to Behçet's syndrome. Differential diagnosis, although not often difficult, must include many conditions capable of producing erosive and ulcerative oral mucosal lesions. The salient features of recurrent aphthous stomatitis suggest that it is a heterogeneous entity. Recent immunologic investigations have focused attention on a possible immunopathogenesis and the evidence for this is reviewed.

Salivary IgA and serum IgG and IgA in recurrent aphthous stomatitis

Salivary flow rate and sIgA were measured in twenty-one patients suffering from recurrent aphthous stomatitis (RAS). Out of this group ten volunteered for continuous study. In these patients salivary IgA and serum IgA and IgG were measured every 3 days for 3 weeks. All parameters were in the physiologic range of healthy people. No correlation with the clinical condition of the patients was found.

Histohogical and direct immunofluorescence study of cutaneous hyperreactivity in Behçet's disease

The mechanism of skin hyperreactivity (pathergy) in Behçet's disease is unknown. It has been suggested that the response is due to an Arthus-like reaction. In 18 patients with active Behcet's disease, pathergy was induced and the skin biopsied after 24 h. The histological reaction was that of mold to intense round cell infiltration. perivascular in type. Direct immunofluorescence failed in all 18 patients to demonstrate the local presence of immunoglobulins and complement at the site of lesion. A marked increase in the number of mast cells was observed at the site of reaction and scattered throughout the dermis, the role of which is to be further investigated. The study failed to demonstrate a humoral mechanism in the production of the cutaneous hyperactivity.

Double blind crossover trial of levamisole in recurrent aphthous ulceration

A double blind crossover trial of levamisole has been carried out in 47 patients with recurrent oral ulceration. Significant decreases in the number of ulcers and ulcer days were found after 2 months of intermittent administration of levamisole. About 64% of patients responded to the drug by a decrease in the number of ulcers of more than 50%, for two or more months. The remaining 36% of patients failed to respond to levamisole and 23% of these had an increased number of ulcers. The side-effects recorded in patients taking levamisole were comparable with those in patients on placebo, except for a flu-like syndrome in 1 patient and urticaria in another, necessitating withdrawal of the drug. The mechanism of action of levamisole in recurrent oral ulceration is not known, but it is suggested that levamisole may correct a deficiency of suppressor cells, or potentiate the cellular responses to crossreacting microbial agents.