Profile of Lymphocytic and Granulocytic Activities in Senegalese Patients with Atopic Dermatitis According to Disease Duration

Atopic dermatitis is an inflammatory skin disease with a juvenile tendency (15% - 20%) of cases with a chronic component that could justify the prevalence in adults (7%). Thus, eczematous-type lesions characterize it across various ethnic phenotypes. This pathology is well known in Europe, America, and Asia, but in Africa, especially in sub-Saharan Africa, poor data are available about atopic dermatitis immunopathology. In this African context, we proceeded to study the physiopathology of this pathology by evaluating the activation levels of immune cells, more specifically the level of lymphocyte activation and the membrane expression levels of the FcεRI-IgE complex on granulocytic cells. Our study is conducted from a descriptive and analytical case-control perspective over a period of 3 months, from December 2, 2021, to March 2, 2022, at Le Dantec medical center. The study population was diagnosed in the dermatology department by specialists based on the analysis of their clinical symptoms with the United Kingdom Working Party (SCORAD, CLDQI/DLQI); Statistical data were carried out using non-parametric tests with significance relief at p < 0.05. Cell analysis was done by flow cytometry with the SYSMEX Cube 8 to assess their activation through membrane expression of the complex FcεRI-IgE on granulocytes and lymphocytes. Overall, neutrophils are the most important cells in patients and healthy subjects, and normal blood lymphocyte levels were observed; no significant differences were observed between patients and controls in these two cell populations. TCD8+ populations are the most blood lymphoid cells isolated (p < 0.001). The levels of eosinophils and basophils obtained in the patients were found to be the highest (p: 0.018; p: 0.149); however, they presented low levels of activation characterized by low membrane expression of FcεRI-IgE on granulocytes. Correlations between disease evolution and IgE/RfcE1 membrane expressions on basophils were found (R₀ = 0.640; p < 0.05; Ro: 0.603, p: 0.027). Indeed, basophils and eosinophils expressing membrane IgE had a similar trend (Ro: 0.634, p: 0.0231). Our results are in contradiction with studies conducted on Afro-Americans and South Africans, in which the Th2 immune response was dominant. This is a preliminary study on A.D in Senegal, so we need to be cautious with these results, given the small number of patients and the need for further immunological and genetic investigations.