Assessment of Platelet-Leukocyte Aggregates Formation in an Experimental Model of Allergic Asthma

Allergic asthma is a Th2-profile inflammatory disease characterized by eosinophilia and elevated serum IgE levels¹. Platelet-leukocyte (P/L) aggregates are observed in asthma, with platelets contributing to the recruitment of granulocytes to the lungs². This study aimed to investigate the association between platelets and leukocytes in the development of asthma in an experimental murine model. Female Balb/c mice (CEUA/UFJF, 35/22) were sensitized and challenged with ovalbumin to induce the asthma model. Blood, lungs, spleen, and bone marrow (BM) were collected for analysis via flow cytometry (FC). The lungs were also used for histological analysis and cytokine quantification. Data were analyzed using Student's t-test, with significance set at *p<0.05, and are expressed as mean differences ± SEM. As expected, allergic responses showed an increase in IL-5 (77.54±30.26), as well as CCL11 (603.1±51.06), associated with an increase in eosinophilic infiltration in the lungs (29.40±1.92). These findings were further supported by FC, which demonstrated elevated production of CD11c-SIGLECF+ (0.97±0.40) in BM, and CD11b+SIGLECF+ (2.47±0.66) and CD4+GATA3+ lymphocytes (7.56±0.94) in the lungs. Interestingly, CD41⁺CD11c^-SIGLECF⁺ and CD41⁺CD11b⁺SIGLECF⁺ aggregates showed a trend toward increase in BM and lungs, respectively. Moreover, CD41⁺CD11c⁺SIGLECF⁺ (3.73±0.94) and CD41⁺CD4⁺RORγt⁺ (6.89±1.16) were significantly increased in the lungs. In the spleen, CD41⁺CD19⁺IgG1⁺ (22.09±4.06) were observed, although CD41⁺CD19⁺IgE⁺ were not detected. Based on the data presented, it is possible to observe the formation of P/L aggregates during allergic asthma, suggesting that this process may occur prior to their arrival in the lungs, as well as in situ. Additionally, the data suggest a potential role for platelets in B lymphocyte class-switching in the germinal center. Acknowledgement: CAPES, CNPQ, FAPERJ, EMBRAPA.

1 Ann Alergia Asma Imunol. (2022)169:180

2 Frente. Imunol. (2022)13:846055