- history of intolerance to l-arginine - severe chronic pulmonary disease - pregnancy or breastfeeding - neutropenia due to neoplasms of the haematopoietic system or other organs with invasion of the bone marrow - use of immunosuppressive drugs or cytotoxic chemotherapies within the previous three weeks - refusal to give consent to participate in the study

- history of intolerance to l-arginine - severe chronic pulmonary disease - pregnancy or breastfeeding - neutropenia due to neoplasms of the haematopoietic system or other organs with invasion of the bone marrow - use of immunosuppressive drugs or cytotoxic chemotherapies within the previous three weeks - refusal to give consent to participate in the study