LTF and allergic rhinitis: Moreover, LTF and C1QA are both multifunctional proteins belonging to the innate immune system.[28] Serum LTF is also a potential biomarker for allergic rhinitis, inherited thrombocytopenia 2, and severe aplastic anemia.[29] C1QA plays a key role in activating complement cascade via the classic pathway as a primary activator, as suggested above.