Early chimerism of macrophages and lymphocytes in lung transplant recipients is predictive of graft tolerance.
BACKGROUND
The persistence of donor cells derived from the graft (chimerism) has been documented in various tissues after organ transplantation. It was suggested that stable chimerism might reflect a state of donor-specific tolerance. Chimerism of macrophages and lymphocytes were studied over time after lung transplantation as well as its impact on graft tolerance.


METHODS
Macrophages and lymphocytes were purified from bronchoalveolar lavage sequentially obtained from 24 patients between 1 and 41 months posttransplantation (20, 22, 24, and 17 patients at, respectively, 1, 3, 6, and 12 months). DNA was extracted from these cells and their recipient-donor origin was evaluated by PCR amplification of highly polymorphic DNA regions (minisatellites).


RESULTS
We show that the remaining donor cells over the first month vary from 10 up to 50% and 5 up to 55% for lymphocytes and macrophages respectively (+/-2 SD). All patients presented some chimerism up to the 6th postoperative month. Good correlation was observed between the residual amount of donor lymphocytes and macrophages during the first 3 months (P<0.001). Patients with at least 30% donor lymphocytes at 1 month after transplantation had less rejections (> or =stage II) in the follow up (P=0.0007). The same observation is true for donor macrophages although to lower extend (P=0.02). The chimerism lost its predictive value beyond 3 months.


CONCLUSIONS
These data demonstrate that a level of chimerism above 30% of either donor lymphocytes or macrophages at 1 month is related to a better state of graft tolerance. However, chimerism decreases markedly beyond 3 months and has then no predictive value.
Rothmeier
C
C
Clinique de Médecine, Hĵpital Cantonal Universitaire de Genève, Geneva, Switzerland.
Roux
E
E
Spiliopoulos
A
A
Gerbase
M
M
Nicod
L P
LP
D000293:Adolescent; D000328:Adult; D002648:Child; D006801:Humans; D016040:Lung Transplantation / Q000276:immunology / Q000473:pathology; D017710:Lymphocyte Transfusion; D016676:Macrophages, Alveolar / Q000637:transplantation*; D008875:Middle Aged; D011237:Predictive Value of Tests; D013997:Time Factors; D018183:Transplantation Chimera; D023001:Transplantation Tolerance / Q000502:physiology