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Langerhans cell deficiency in reticular dysgenesis
J F Emile1, F Geissmann, O C Martin
1Service d'Anatomie Pathologique, Hôpital Paul Brousse, and UPRES 1596, Université Paris-Sud, Villejuif, France. francois.emile@pbr.ap-hop-paris.fr
Blood
|July 13, 2000
Summary
Reticular dysgenesis, an inherited immunodeficiency, affects Langerhans cells but not all macrophages. A bone marrow-derived factor may cause this defect, not an intrinsic cell issue.
Area of Science:
- Immunology
- Cell Biology
- Genetics
Background:
- Reticular dysgenesis is a rare inherited immunodeficiency.
- It is characterized by a lack of blood monocytes and neutrophils, with low lymphocyte counts.
- The impact on dendritic cells and macrophages, which derive from monocytes, was previously unknown.
Purpose of the Study:
- To investigate the differentiation of macrophages and dendritic cells in patients with reticular dysgenesis.
- To determine if the defect in reticular dysgenesis is intrinsic to the cells or due to a bone marrow-derived factor.
Main Methods:
- Studied 7 patients with reticular dysgenesis.
- Examined macrophage presence in dermal and lymphoid tissues.
- Assessed Langerhans cell (CD1a-positive epidermal dendritic cells) presence before and after bone marrow transplantation.
- Analyzed monocyte differentiation in a patient with successful engraftment.
Main Results:
- Macrophages were present in normal numbers in dermal and lymphoid tissues.
- Langerhans cells were absent in all patients before bone marrow transplantation but present after transplantation in some.
- A patient with successful engraftment showed autologous blood monocytes differentiating into CD1a-positive dendritic cells.
Conclusions:
- The results suggest that macrophages can differentiate despite low monocyte counts in reticular dysgenesis.
- The absence of Langerhans cells indicates a defect not related to keratinocyte dysfunction.
- An intrinsic cell defect is unlikely; a defective bone marrow-derived factor may cause the Langerhans cell defect but not affect macrophage differentiation.