Serine protease P er a 10 from P eriplaneta americana bias dendritic cells towards type 2 by upregulating CD 86 and low IL ‐12 secretions

Summary Background Serine protease activity of P er a 10 from P eriplaneta americana induces airway inflammation and systemic Th 2 response towards self and bystander allergen. Objective In the present study the effect of proteolytic activity of P er a 10 allergen on dendritic cells ( DC s) polarization and consequent T cell response was investigated. Methods Non‐atopic subjects with no family history of asthma/allergy were recruited for the study. CD 14 + peripheral blood monocytes were purified, differentiated to immature DC s and stimulated with proteolytically active/inactivated native or recombinant P er a 10. DC s phenotype was analysed with flow cytometry and antigen presenting function assessed by co‐culturing with autologous CD 4 + T cells. Cytokine levels were determined using ELISA . Results Immature DC s differentiated into mature CD 14 ‐ CD 83 + HLA ‐ DR + cells after incubating with proteolytically active/inactivated or recombinant P er a 10. Proteolytically active P er a 10 induced significant CD 86 up‐regulation on DC s compared to inactivated or recombinant P er a 10 lacking enzymatic activity. Proteolytic activity of P er a 10 showed dose‐dependent effect on expression of CD 80, CD 86, CD 83, CD 1a and HLA ‐ DR . However, no significant differences were observed phenotypically in active or inactive forms except for CD 86. Active P er a 10 stimulated DC s secreted significantly low IL ‐12 ( P  <   0.01) and high IL ‐6, compared to inactive forms of P er a 10. Naive CD 4 + T cells primed with active P er a 10 pulsed DC s also secreted significantly less IL ‐12 ( P  <   0.01) and high IL ‐4, IL ‐5 plus IL ‐6 ( P  <   0.01); in contrast to DC s pulsed with inactivated or recombinant P er a 10. Conclusion and clinical relevance Proteolytic activity of P er a 10 modulates DC s towards type 2 by CD 86 up‐regulation, high IL ‐6 and reduced IL ‐12 secretions. Proteolytically inactive P er a 10 can be further explored for immunotherapy.