Edwin B. Howard

COMPOSITE TISSUE (LIMB) ALLOGRAFTS IN RATS: II. INDEFINITE SURVIVAL USING LOW-DOSE CYCLOSPORINE

Cyclosporine has reawakened interest in transplantation of peripheral composite tissue allografts (CTA) of skin, muscle, bone, vessel, and nerves. The purpose of this study was to examine whether cyclosporine could produce indefinite survival of CTA. Two groups of LEW recipients of LBN limb transplants were given different long-term treatments of cyclosporine. Tolerance was achieved in many of the animals. Several possibilities for the mechanism of this tolerance are discussed.

Composite tissue (limb) allografts in rats. III: Development of donor-host lymphoid chimeras in long-term survivors

Eight LEW rat recipients possessing long-term-surviving (206-701 days) LBN vascularized hind limb allografts (CTAs) were tested for donor-host lymphoid chimerism. The recipients received various cyclosporine (CsA) treatment protocols in order to induce indefinite CTA acceptance. Histological examination of long-term-surviving CTAs demonstrated normal-appearing bone marrow in the donor limb. Lymphocytes isolated from host hemopoietic tissues (peripheral blood and/or spleen) by ficoll-hypaque density gradient centrifugation were tested against LEW-anti-BN antisera. Comparisons were made to standard curves employing various known concentrations of LBN and LEW cell combinations. The level of lymphocyte agglutination (dependent variable) showed a significant (P less than 0.025-0.005) linear relationship to the concentration of LBN donor cells (independent variable) present. Lymphocyte suspensions isolated from long-term CTA host peripheral blood and/or spleen showed a mean of 19.7% (+/- 9.7-95% confidence interval) donor LBN mononuclear cells present. Thus, it appeared that lymphoid cells originated from, and/or were released from LBN donor bone marrow into the circulation, resulting in chimeric repopulation of hemopoietic tissues. The presence of donor immunocytes in these limb allograft recipients may have been beneficial, and thus could have helped contribute to the long-term CTA survival observed.

Composite tissue (limb) allografts in rats. I: Dose-dependent increase in survival with cyclosporine

The dose-response effect of cyclosporine on rat limb transplant prolongation was investigated across the LBN-to-LEW histocompatibility barrier. This composite tissue allograft model has been shown to represent a strong transplantation barrier. Median limb allograft survival times increased in a dose-dependent manner with low cyclosporine doses, and then reached a plateau at higher levels. The cyclosporine dose that produced half-maximal survival based on a 20-day treatment was only 3.7 mg/kg/day. Histopathology revealed that the rejection process was distinctly different in limb allografts treated with cyclosporine compared with noncyclosporine-treated controls. Rejection appeared to be delayed or partly arrested in certain areas of cyclosporine-treated limb allografts. These studies represent an initial step in laying the experimental foundation for clinical transplantation of composite tissue allografts using cyclosporine-induced immune suppression.

Cyclosporine and skin allografts for the treatment of thermal injury. I. Extensive graft survival with low-level long-term administration and prolongation in a rat burn model.

The hypothesis tested in the present and accompanying study is that and effective treatment for severe burns involves early excision of necrotic tissute followed by skin allografting ad cylosporine (CsA) immunosuppressive therapy. LEW (RR11) rats served as recipients of thermal injury and/or skin allografts. BNxLEW F1M (LBN, RT11+n) rats served as skin donors. LEW burn recipients received a hot water (90oC for 10 sec) 30% body surface area (BSA) full-thickness burn. As expected, LEW recipients treated with CsA (25 mg/kg/day for 20 days) demonstrated singnificant graft polongation compared with controls (P<0.005). Skin graft survival was similarly prolonged in LEW recipeints undergoing burn unjury, primary wound excision, and CsA administration comkpared with not increased in the thermal injury—CsA-treated recipients comkpared with burn controls. A final experiment was initiated to investigate how low-level long-term (>100 days) maintenace CsA treatment influenced skin allograft survivalfor possible future consideration in burn trauma. Recipioents receiving skin allografts plus CsA (20 days, 8mg/kg/day, followed by every other day therafter) did not reject their grafts. However, a possible early sign of rejection ( a gingle small ulceratiove lesion) was noted in five of these long-term CsA-treated animals at a meanof 3411 (SD) days. The lesion in these animals did not progress any further during CsA administration. His-topathologic study of selected animals removed from the CsA maintenance regimen for greter than 50 days following long-term administration revealed a number of interesting chronic lesions similar to thosse previously reported in the skin comonent of composite tissue (limb) allografts following long-term low-level CsA intervention. In conclusion, CsA was very successful in preventing rejection of skin allografts in a rat burn model without apparent adverse effects.

Decreased reactivity of allosera against target lymphocytes obtained following thermal injury or long-term cyclosporine treatment☆☆☆

We speculated that two diverse causes of potent cell-mediated immune suppression, cyclosporine (CsA) and thermal trauma, may demonstrate some similar actions, and thus tested whether either could alter antisera reactivity against allogeneic target lymphocytes. Target splenocytes from 40% body surface area full-thickness burned Brown-Norway (BN) rats demonstrated significant (P = 0.004) decreased reactivity (agglutination) with antisera produced across a full allogeneic barrier (RT1 major histocompatibility complex (MHC) and non-MHC) compared to control splenocytes. Depression of allogeneic splenic target cell reactivity against Lewis (LEW)-anti-BN allosera was similarly observed using lymphocytes from long-term CsA-treated rats (P = 0.004). The decreased reactivity induced by burn trauma was transferable to pooled normal splenocytes or blood lymphocytes by preincubation with burn plasma (P less than 0.001), and was confirmed by a cellular enzyme-linked immunosorbent assay (CELISA) (P = 0.003). In summary, a similarity consisting of decreased antibody reactivity against lymphocytes from either burned or long-term CsA-treated animals was demonstrated. These results suggested that lymphocyte cell surface allogeneic determinants and their expression and/or availability were altered by either regimen.

Urinary tract infection after injection of pseudomonas into bladder

Pseudomonas urinary tract infection was studied in female mice. The bladder was exposed by a lower midline incision and an overnight washed culture of Pseudomonas (0.05 ml.) was injected into the bladder. This resulted in infection of the kidneys in more than 50 per cent of mice at one week. At four hours, the microulceration of the bladder was observed with many Pseudomonas int the base of the ulcer. The presence of acute inflammation on the serosal surface of the bladder, the frequent death of the mice, the presence of cortical foci of polymorphonuclear leukocytes in the kidneys, and bacteremia suggested that bacteremia may play a significant role in the development of the renal infection in this model of urinary tract infection. Bacteria injected through the bladder wall of mice cannot be assumed to produce ascending infection of the kidney.