Impaired antigen-presenting cell function contributes to T-cell hyporesponsiveness in stable lung transplant recipients.
BACKGROUND
Peripheral blood mononuclear cells (PBMC) of stable renal or cardiac transplant recipients were previously shown to respond to allogeneic cells but not to soluble protein antigens. The aim of the present study was to assess the T-cell and antigen-presenting cell (APC) functions of stable lung transplant (LT) recipients.


METHODS
We obtained PBMC from 38 stable LT recipients. PBMC from healthy volunteers served as controls. PBMC were stimulated with either anti-CD3 monoclonal antibody, allogeneic PBMC, or tetanus toxoid (TT). T-cell activation was assessed by determination of interleukin (IL)-2 levels in culture supernatants; in some experiments, interferon-y levels were also determined. Patients' APC function was tested in a mixed leukocyte reaction using patients' PBMC as stimulators. The expression of class II MHC, B7.2, and CD40 molecules on patients' APC was determined by flow cytometry, and their production of IL-10 and IL-12 at the basal state and upon CD40 ligation was also measured.


RESULTS
Patients' T cells produced normal amounts of IL-2 in response to anti-CD3 monoclonal antibody and allogeneic PBMC. In contrast, the response of memory T cells to TT was severely blunted both in terms of IL-2 and interferon-y production. Patients' PBMC were poor stimulators in mixed leukocyte reaction, and class II MHC expression on patients' monocytes was significantly reduced. Patients' APC presented a modest but significant increase in basal IL-10 production and produced significantly less IL-12 upon CD40 ligation than control APC.


CONCLUSIONS
T cells from stable LT recipients respond normally to stimuli that do not depend on autologous APC. The major impairment in the T-cell response to TT is caused by APC dysfunction, which involves decreased class II MHC expression and deficient IL-12 synthesis.
Knoop
C
C
Department of Chest Medicine, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium.
Ismaili
J
J
Bulté
F
F
Abramowicz
D
D
Estenne
M
M
Goldman
M
M
D000938:Antigen-Presenting Cells / Q000502:physiology*; D002478:Cells, Cultured; D006684:HLA-DR Antigens / Q000032:analysis; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D016753:Interleukin-10 / Q000378:metabolism; D018664:Interleukin-12 / Q000172:deficiency; D007519:Isoantigens / Q000276:immunology; D016040:Lung Transplantation / Q000276:immunology*; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D016853:Muromonab-CD3 / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D013745:Tetanus Toxoid / Q000494:pharmacology
D006684:HLA-DR Antigens; D007166:Immunosuppressive Agents; D007519:Isoantigens; D016853:Muromonab-CD3; D013745:Tetanus Toxoid; D016753:Interleukin-10; D018664:Interleukin-12