Vol. 5, Issue 1, Part A (2023)

Extracellular traps (ETs) are structures composed of chromatin, histones and granular proteins, which constitute a functional microbicidal mechanism of immune cells. Currently, its participation in the pathophysiology of various pathologies, including COVID-19, autoimmune diseases and cancer, has been studied. Costimulatory B7 molecules (B7-1:CD80 and B7-2:CD86) provided the second activation signal for T cells. In this research, the study of the influence of colocalized B7 molecules in ETs was carried out in vitro from leukocytes on T-cell activation and CD45 RO expression in neutrophils in autologous human blood cell cultures. Objectives: to generate and isolate ETs in autologous cultures of leukocytes exposed to lipopolysaccharide (LPS); labelling B7 molecules in isolated ETs, CD4 co-receptor expression and CD45RO activation marker in interaction assays with ETs and autologous leukocytes in culture. Methods: autologous leukocytes cultures from healthy human blood samples anticoagulated with heparin, (n = 10) with informed consent (Ethics Committee, HNC, FCM), were stimulated with 25 ng/ml of LPS, 30 minutes. Subsequent isolation technique. Immunofluorescence technique with anti-CD80, anti-CD86, anti- CD4 and anti-CD45RO was performed, DNA staining: DAPI. Controls: paired blood samples. Statistical treatment: t-test for paired samples. Results: At 24 hours of culture, no significant differences (p<0.05) were observed in percentages of CD4 and CD45RO positive cells between paired control samples and ETs addition samples. At 72 hours of culture, significant differences (p<0.05) were observed in CD45RO expression between controls and ETs addition samples. In one donor, significant differences (p<0.05) were observed in CD4-positive cells percentage. The presence of B7 molecules could give the second signal required for the activation of autoreactive T lymphocytes present in the autologous culture, implying the possibility of breaking self-tolerance.