Quantitation of immunosuppression by flow cytometric measurement of the capacity of T cells for interleukin-2 production.
BACKGROUND
Methods to quantitate the effects of immunosuppressive drugs on immune reactivity might be helpful for monitoring immunosuppressive treatment. Cyclosporine (CsA) inhibits the induction of cytokine synthesis in T cells, and measurement of interleukin (IL)-2 production might constitute a parameter of this drug's effect.


METHODS
We determined the percentages of CD4+ and CD8+ lymphocytes producing IL-2 upon stimulation by phorbol myristate acetate and calcium ionophore in whole blood culture, using immunostaining of intracytoplasmatic and membrane markers, followed by multiparameter flow cytometry. A total of 38 clinically stable transplant patients on various immunosuppressive protocols were studied.


RESULTS
The percentage of CD4+ T cells producing IL-2 was strongly reduced in patients compared with healthy controls (23% [range, 3-68%] vs. 59.0% [range, 41-70%]; P=0.000035). The percentage of CD4+ T cells producing IL-2 was negatively correlated with the CsA level (Rc=-0.0821, P=0.00002297) but not with prednisolone or azathioprine doses. Fewer CD8+ T cells produced IL-2 in transplant patients compared with controls, but the difference failed to reach statistical significance. The percentage of CD8+ T cells capable of producing IL-2 was inversely correlated to CsA levels (Rc=-0.0375, P=0.0011).


CONCLUSIONS
These data suggest that the functional effects of CsA in transplant recipients can be quantitatively determined and that the capacity of CD4+ T cells to produce IL-2 upon stimulation constitutes a functional parameter of CsA effects on the immune system. Prospective studies are required to determine whether this method is useful for clinical monitoring.
van den Berg
A P
AP
Department of Gastroenterology and Hepatology, University Hospital, Groningen, The Netherlands.
Twilhaar
W N
WN
Mesander
G
G
van Son
W J
WJ
van der Bij
W
W
Klompmaker
I J
IJ
Slooff
M J
MJ
The
T H
TH
de Leij
L H
LH
D000328:Adult; D000368:Aged; D001379:Azathioprine / Q000627:therapeutic use; D001803:Blood Transfusion; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002478:Cells, Cultured; D016572:Cyclosporine / Q000493:pharmacokinetics / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006650:Histocompatibility Testing; D006801:Humans; D007165:Immunosuppression Therapy; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007376:Interleukin-2 / Q000096:biosynthesis*; D016030:Kidney Transplantation / Q000276:immunology*; D016031:Liver Transplantation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D015166:Monitoring, Immunologic / Q000379:methods*; D010298:Parity; D011239:Prednisolone / Q000627:therapeutic use; D012016:Reference Values; D013601:T-Lymphocytes / Q000276:immunology*
D007166:Immunosuppressive Agents; D007376:Interleukin-2; D016572:Cyclosporine; D011239:Prednisolone; D001379:Azathioprine