Distribution of Dipeptidyl Peptidase IV in Patients with Chronic Tonsillitis

Abstract

In the pathogeneses of recurrent tonsillitis (RT) and tonsillar hypertrophy (TH), different immunological mechanisms are involved. Dipeptidyl peptidase IV (DPP IV) and aminopeptidase N (APN) participate in the regulation of the immune response during inflammation. In this study, the localization of DPP IV and the enzymatic activities of DPP IV and APN in 32 patients, 13 with RT and 19 with TH, who underwent tonsillectomy were investigated. The localization of DPP IV in tonsils was studied using histochemical and immunohistochemical methods. The enzymatic activities of DPP IV and APN in tonsillar lymphocytes and the patients' sera were determined kinetically at 37°C using Gly-Pro-p-nitroanilide (for DPP IV) and Ala-pnitroanilide (for APN) as chromogenic substrates. In samples from both RT and TH patients, DPP IV was found to localize mainly in extrafollicular areas of tonsillar tissue in a pattern corresponding to the T-cell distribution. Significantly higher (P < 0.001) levels of DPP IV and APN activities in sera from patients with TH than in sera from patients with RT were found. A correlation of DPP IV activities in sera and tonsillar lymphocytes from patients with TH was also found (r ‫؍‬ 0.518; P < 0.05). Moreover, the results show that DPP IV and APN activities in sera decreased significantly with age. Tonsillar lymphocytes demonstrated a wide range of DPP IV and APN activities, without significant differences between the investigated groups. The results of this study show that the localization of DPP IV does not depend on the type of tonsillitis, whereas the variety in levels of DPP IV and APN activities in sera of patients with TH and RT suggests different patterns of participation of antigen-stimulated tonsils in the immune system.

Activity of soluble aminopeptidase A and dipeptidyl peptidase IV and membrane-bound aminopeptidase B and pyroglutamyl peptidase I in adenoid hyperplasia, tonsillar hyperplasia and chronic tonsillitis

“…The pattern of activity shown by these enzymes differed depending on patient age and gender as well as their medical condition. This selective pattern has also been described in previous studies [1,3,7] and demonstrates that the changes observed are not the result of nonspecific cell proteolysis.…”

“…Membrane-bound DPPIV (EC 3.4.14.5) activity is higher in CT than in the hyperplastic conditions [3,7]. Furthermore, in CT tissues this activity is higher in adults than in children and in males than in females.…”

Altered dipeptidyl peptidase IV and prolyl endopeptidase activities in chronic tonsillitis, tonsillar hyperplasia and adenoid hyperplasia

“…A recent study demonstrated that DPPIV was mainly expressed in the extrafollicular areas of tonsils in CT and TH patients [4]. Immunofluorescence analysis also showed moderate fluorescence of this enzyme in the germinal centres of follicles of CT patients, suggesting that this activity may correspond to the T-helper cell functions.…”

“…[ ( ) T D $ F I G ] Interestingly, when looking at the DPPIV activity in patients with CT as a function of age, we found that it was significantly higher in the samples from the adult group (>14 years old) than those from the children. In relation to this, Stankovic et al [4] reported that the level of DPPIV in serum from individuals with CT was higher the younger the patient.…”

“…However, there are relatively few such studies and their scope has been restricted to a few enzymes [4].…”