Idiopathic CD4+ lymphocytopenia may be due to decreased bone marrow clonogenic capability.
BACKGROUND
Idiopathic CD4+ lymphocytopenia is defined by a stable decrease of CD4+ T cells in the absence of any known cause of immune deficiency. The mechanisms responsible for the immunological impairment are still unknown, but a regenerative failure of hematopoietic stem/progenitor cells has been hypothesized.


METHODS
We evaluated in the bone marrow (BM) of 5 patients with idiopathic CD4+ lymphocytopenia the phenotype of BM progenitor cells, their differentiation capacity with colony-forming cells and long-term culture-initiating cell assays, in parallel with the spontaneous IL-7 production in the patient sera.


RESULTS
Compared with controls, a regenerative failure of hematopoietic stem cells has been observed, both in 'committed' and in 'uncommitted' progenitor cells, despite high IL-7 serum levels. The percentage of phenotypically primitive CD34+CD38-DR+ cells (this includes the lymphoid precursor cells) was decreased, suggesting an involvement of the more primitive BM compartment in the de novo T cell generation.


CONCLUSIONS
Despite the low number of patients, due to the low incidence of the disease, the decrease of primitive precursors sustains the possibility that diminished stem cell precursors might contribute to the development of CD4+ T cell depletion.
Isgrò
Antonella
A
Division of Allergy and Clinical Immunology, University of Rome La Sapienza, Rome, Italy.
Sirianni
Maria Caterina
MC
Gramiccioni
Claudia
C
Mezzaroma
Ivano
I
Fantauzzi
Alessandra
A
Aiuti
Fernando
F
D000328:Adult; D001853:Bone Marrow / Q000276:immunology*; D005260:Female; D006801:Humans; D015851:Interleukin-7 / Q000097:blood; D008297:Male; D008875:Middle Aged; D018344:T-Lymphocytopenia, Idiopathic CD4-Positive / Q000209:etiology* / Q000276:immunology / Q000378:metabolism
D015851:Interleukin-7