What is your approach to further evaluation/testing when autoimmune neutropenia is suspected but anti-neutrophil antibodies are negative?

What is your approach to further evaluation/testing when autoimmune neutropenia is suspected but anti-neutrophil antibodies are negative?

• Repeat anti-neutrophil antibody testing serially
• Expand to evaluation of secondary causes for neutropenia, such as for autoimmune or immunodeficiency causes
• Consider bone marrow evaluation
• Other