Allergies And Immulogic Diseases

Páginas: 5 (1052 palabras) Publicado: 18 de junio de 2012
Allergies and immulogic diseases
Chapter outline
Recurrent Aphthous Ulcerations
Major aphthous ulcerations
Herpetiform aphthous ulcerations

Recurrent aphthous stomatitis is one of the most common oral mucosal pathoses. The reported prevalence in the general population varies from 5% to 66%. With a mean of 20%.The hypotheses of its pathogenesis are numerous. As soon as one investigator claims to have discovered the definitive cause, a subsequent report discredits the discovery. Different subgroups of patients appear to have different causes for the occurrence of aphthae. These factors suggest a disease process that is triggered by a variety of causative agents, each of which is capable of producing thedisease in certain subgroups of patients. To state it simply, the cause appears to be “different things in different people.”
Although no single triggering is responsible, the mucosal destruction appears to represent a T cell mediated immunologic reaction. Analysis of the peripheral blood in patients whit aphthae shows a decreased ratio of CD+ To CD8+ T Lymphocytes, increased T cell- receptory8+ cells, and increased tumor necrosis factor-a. When developing aphthae have been investigated locally, a heavy inflammatory infiltrate is noted, and approximately 8O% of the cells in the affected mucosa and underlying lamina propria are T lymphocytes. Although some investigators suggest the process may involve an antibody-dependent cellular cytotoxicity, most believe the destruction is due to adirect T lymphocyte-mediated cytotoxicity. Evidence of the destruction of the oral mucosa mediated by these Lymphocytes is strong, but the initiating causes are elusive and most likely highly variable.
The following all have been reported to be responsible in certain subgroups of patients (and each discounted in other subgroups!):
* Allergies
*Genetic predisposition
* Nutritional deficiencies* Hematologic abnormalities
*Hormonal influences
* Infectious agents
* Trauma

When all the various subgroups are combined, the various causations cluster into three categories:
I. Primary immunodysregulation
2. Decrease of the mucosal barrier
3. Increase in antigenic exposure
One or more of these three factors may be involved in subgroups of patients.
Recurrent aphthousstomatitis demonstrates a definite tendency to occur along family lines. In addition, several investigators support genetic predisposition; these clinicians have associated certain histocompatibility antigen (HLA) types with subgroups of patients with aphthous stomatitis. HLA-B12, B51, and Cw7 are some of the numerous types that have been mentioned; as expected, however, these findings are not presentconsistently. Interestingly, the predominantly mucocutaneous form of Behcet's syndrome (Behcet's disease) (see page 29O) exhibits significant aphthousIike oral ulcerations and also has been associated with HLA-B 12. Two other disorders Crohn’s disease (see page 733) and celiac disease-have been associated with certain HLA types and exhibit an increased frequency of aphthousIike ulcerations.Stress, with its presumed effects on the immune system, directly correlates with the presence of aphthous stomatitis in some groups. In studies of professional students, recurrences clustered around stressful periods of the academic year; conversely, periods of vacation were associated with a low frequency of lesions.
Aphthous Like ulcerations have occurred in patients with systemic immunedysreguLation. Patients with cyclic neutropenia (see page 5O7) occasionally have cycles of aphthous like ulcerations that correspond to the periods of severe immune dysregulation. Resolution of the neutropcenia terminates the cycle of ulcerations. In addition, patients with acquired immunodeficiency syndrome (AIDS) have an increased frequency of severe aphthous stomatitis (see page 293). This...
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