Rat renal allograft tolerance is associated with local TGF-beta and absence of IL-2r expression within chimeric immunocytic foci.
Tolerance was induced in Lewis (LEW) rat renal allograft recipients of Brown Norway kidneys by multiple pretransplant donor-blood transfusions and prior limited cyclosporine A. Rat renal allograft tolerance was associated with the induction of systemic donor T cells (10%), an early phase of nonspecific suppressor-cell generation, followed by maturation of systemic antigen-specific suppressor cells, and renal cellular infiltrates that develop long-term in situ in the kidney graft model. It was hypothesized that these infiltrates represent chimeric immunocytic foci that are locally regulated via a TGF-beta-dependent mechanism. Both immunohistochemical staining and digital image analysis for cellular and extracellular TGF-beta, IL-2 receptor (CD25), and the BN Class I-MHC marker (OX-27) were performed. Control rejecting (REJ) kidneys did not demonstrate any differences with respect to levels of infiltrating immunocyte area vs long-term surviving (TOL) kidneys (3.9% vs 4.5%, P = .303). Immunostaining with the BN Class I MHC marker (OX-27) demonstrated high levels of chimerism within immunocyte foci of the tolerant grafts (OX-27 BN+immunocytes 49.0% +/- 5.1%). In situ cellular IL-2 receptor (CD25) expression was demonstrated in REJ kidney infiltrates but not within TOL immunocytic infiltrating foci, when measured as percent of total lymphocytes (REJ = 5.0% vs TOL = 0.4%, P = .031). Conversely, TGF-beta expression was significantly higher in immunocytes of TOL kidneys when measured as the number of DAB chromogen-staining pixels per total immunocyte area (TOL = .076 vs REJ = .047, P = .003). In conclusion, these results suggested that stable mixed immune chimerism (SMIC) plays an important role in DST-CyA-induced tolerance in situ. SMIC-induced tolerance may involve a local TGF-beta-dependent mechanism that is associated with in situ TGF-beta (+) and IL-2r (-) immunocytes.
Hewitt
C W
CW
Department of Surgery, Robert Wood Johnson Medical School, Cooper Hospital/University Medical Center, Camden, New Jersey, USA.
Strande
L
L
Santos
M
M
Goodman
M
M
Tarnoff
M
M
Zaontz
M R
MR
DelRossi
A J
AJ
Doolin
E J
EJ
D000818:Animals; D001803:Blood Transfusion; D006085:Graft Survival; D007150:Immunohistochemistry; D007165:Immunosuppression Therapy / Q000379:methods*; D016030:Kidney Transplantation / Q000276:immunology* / Q000473:pathology; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis*; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000032:analysis*; D018183:Transplantation Chimera; D014184:Transplantation, Homologous
D015375:Receptors, Interleukin-2; D016212:Transforming Growth Factor beta