Leukocyte adhesion deficiency (LAD) is a rare inborn error of immunity characterized by defective leukocyte trafficking leading to severe bacterial infections and early mortality without hematopoietic stem cell transplantation (HSCT). In 2011, our center reported outcomes of 11 patients with LAD type I. We now present an expanded cohort including LAD-I and -III, with extended follow-up and contemporary transplant approaches.
We performed a retrospective analysis of patients with genetically or immunophenotypically confirmed LAD who underwent allogeneic HSCT at a tertiary immunodeficiency center between 2010 and 2026. Data collected included LAD subtype, donor source, conditioning regimen, graft characteristics, graft versus host disease (GVHD) incidence, survival, and immune reconstitution including CD18 expression and lineage-specific chimerism.
13 patients underwent HSCT (10 LAD-I, 3 LAD-III). Median age at transplant was 6 months (interquartile range 4–14). Donors included matched sibling (n = 4), other family donors (n = 5), unrelated donors (n = 2), and cord blood (n = 2). All patients received busulfan (Bu)-based conditioning (Bu/cyclophosphamide ± antithymocyte globulin [ATG] or Bu/fludarabine ± ATG). With a median follow-up of 10.2 years among survivors, overall survival was 84.6% (11/13). Survival was 80% in LAD-I and 100% in LAD-III. Two deaths occurred in LAD-I, including one graft failure requiring second HSCT and one late infectious mortality. Acute GVHD occurred in 15% and was limited; no severe chronic GVHD was observed. Durable immune correction was achieved in the majority of survivors. Among evaluable LAD-I patients, post-HSCT neutrophil CD18 expression was high (median 96.5%), though two long-term survivors demonstrated stable mixed chimerism with partial CD18 correction (41–49%) and remained clinically well.
In this expanded single-center experience, allogeneic HSCT provides durable survival and sustained immune correction in LAD types I and III. Compared to our earlier report, outcomes remain favorable with low rates of severe GVHD and acceptable graft failure risk. Mixed chimerism with partial CD18 expression may be sufficient for long-term clinical stability, underscoring the importance of functional immune reconstitution rather than full donor chimerism alone.
