LOW pH ENHANCES NEUTROPHIL TROGOCYTOSIS

RIVELLI, FEDERICO; BOGADO, MELISA; BLEICHMAR, LUCÍA; MAZZITELLI, IGNACIO; MAZZITELLI, BIANCA; ERRA DIAZ, FERNANDO; GEFFNER, JORGE

San Luis

Congreso; Reunion Anual Sociedad Argentina Inmunologia 2023; 2023

Trogocytosis is a biological process by which cells acquire membrane fragments from donor cells through a contact-dependent process, allowing the acquisition of receptors that can modulate the function of receiving cells. Trogocytosis has been shown to be involved in different processes including cell-cell communication, antigen-presentation, immune regulation, and anti-tumor immunity. However, the mechanisms involved in this process remain poorly characterized. We here analyzed whether low pH values (pH 6.5), similar to those found in inflammatory processes, could modulate neutrophil-mediated trogocytosis. Neutrophils were isolated from peripheral blood from healthy donors using conventional methods. Jurkat (a T cell line) and Ramos (a B cell line) were used as donor cells, and were previously coated or not with anti-CD3 or anti- CD20 IgG antibodies, respectively. Afterward, neutrophils were co-cultured at 37°C for 2 hours with either Jurkat or Ramos cells using a cell-cell ratio of 1:1, at pH 7.3 or pH 6.5. In a first set of experiments, Jurkat cells were stained with the lipophilic dye PKH-26, which labels the cell membrane, and the transference of PKH-26 to neutrophils was evaluated by flow cytometry. No transference of PKH was observed when using unopsonized Jurkat cells (not shown). By contrast, we found that 49 ± 12 % and 96 ± 14% of neutrophils were PKH-26 positive at pH 7.3 and pH 6.5, respectively (n=3, p