In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

Steady state alveolar macrophages (AM) are long-lived lung-resident macrophages with sentinel function. Evidence suggests that AM precursors originate during embryogenesis and populate lungs without replenishment by circulating leukocytes. However, their presence and persistence are unclear following human lung transplantation (LTx). Our goal was to examine donor AM longevity and evaluate whether AM of recipient origin seeds the transplanted lungs. Origin of AM was accessed using donor-recipient HLA mismatches. We demonstrate that 94-100% of AM present in bronchoalveolar lavage (BAL) were donor derived and importantly AM of recipient origin were not detected. Further, analysis of BAL cells up to 3.5 yrs post-LTx revealed that majority of AM (>87%) was donor derived. Elicitation of de novo donor specific antibody (DSA) is a major post-LTx complication and a risk factor for development of chronic rejection. The donor AM responded to anti-HLA framework Ab with secretion of inflammatory cytokines. Further, in an experimental murine model, we demonstrate that adoptive transfer of allogeneic AM stimulated humoral and cellular immune responses to alloantigen and lung-associated self-antigens and led to bronchiolar obstruction. Therefore, donor derived AM play an essential role in the DSA induced inflammatory cascade leading to obliterative airway disease of the transplanted lungs.
Long-term persistence of donor alveolar macrophages in human lung transplant recipients that influences donor specific immune responses HHS Public Access