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Blood ciclosporin (Cs) metabolite pattern in 58 liver grafted patients was routinely monitored by HPLC from the first Cs dose after transplantation until discharge from hospital. Eighteen patients with normal kidney function were allocated to Group I and 14 patients in Group II suffered Cs nephrotoxicity during their clinical course. There were no significant differences between both groups in blood Cs level, kidney function before transplantation, liver function or co-administration of other potentially nephrotoxic drugs. A correlation matrix involving both groups showed a significant correlation between the blood concentration of metabolite M1c9 and serum creatinine and urea, and an inverse correlation with creatinine clearance. During a nephrotoxic episode the blood concentrations of metabolites M1c9 and M1A were significantly elevated in patients in Group II. Analysis of the time course revealed significantly higher blood levels of M19 and M1c9 in Group II patients compared with those in Group I for the first 10 days after transplantation. Serum creatinine and urea concentrations remained significantly elevated, the creatinine clearance being significantly reduced throughout the period of observation. The elevated blood concentrations of ciclosporin metabolites M1c9 and M19 during nephrotoxic episodes suggest that these metabolites are associated with ciclosporin nephrotoxicity. It could not be decided if the elevated metabolite concentrations were the result of and/or the reason for impaired kidney function.

The effects of COS7 cells which constitutively express the apoptosis-inducing human CD95 ligand (COSh95L cells) on in vitro alloimmune responses were investigated. In the presence of COSh95L cells a clear-cut inhibition of alloantigen-induced proliferation was observed. In these cultures fully activated blastoid T cells were absent suggesting that deletion of activated T cells is one mechanism of COSh95L-mediated inhibition of proliferation. Non-fully activated cells were not eliminated in MLR by COSh95L cells but achieved a hyporesponsive state as shown by their failure to proliferate in response to restimulation with alloantigen or mitogen. These data indicate that the effects of CD95L on T cells are heterogeneous. Further analysis of the actions of CD95L in T cells of different activation states and subsets will be crucial to estimate the therapeutical potential of this molecule as target for immunomodulation after allo- and xenotransplantation.

The critical shortage of human donor organs has generated growing interest for porcine to human xenotransplantation. The major immunological barrier to xenotransplantation is the hyperacute rejection (HAR) response that is mediated by preformed xenoreactive antibodies and complement. A promising strategy to control the complement activation, is the expression of human complement regulatory proteins in transgenic animals. We have used the human early cytomegalovirus (CMV) promoter to drive expression of the human complement regulatory protein CD59 (hCD59) in transgenic pigs. A total of eight live transgenic founder animals was born from which five transgenic lines could be established. mRNA analysis and Western blotting revealed high expression of hCD59 in heart, kidney, skeletal muscle, and skin in animals of lines 1 and 5, as well as in the pancreas of four lines. This pattern of expression was confirmed by immunhistological staining. A cell-specific expression in heart and kidney tissue of transgenic lines 1 and 5 was determined. Primary fibroblasts and endothelial cell cultures derived from the aorta of transgenic pigs showed a significantly diminished sensitivity against the challenge with xenoreactive human antibodies and complement whereas non-transgenic control cells were highly susceptible to complement mediated lysis. Ex vivo perfusion of kidneys with pooled human blood revealed a significant protective effect of hCD59 against HAR. The average survival of transgenic kidneys was significantly extended (P0.05) over nontransgenic controls (207.5+/-54.6 vs. 57.5+/-64.5 min). These data support the concept that hCD59 protects nonprimate cells against human complement mediated lysis and suggest that donor pigs transgenic for hCD59 could play a crucial role in clinical xenotransplantation. Two of five hCD59 transgenic lines showed strong hCD59 expression in several organs relevant for xenotransplantation and a protective effect against HAR. This indicates that the use of the CMV-promoter can facilitate the selection process for optimized transgene expression.

In clinical organ transplantation monoclonal antibodies (mAb) to different surface molecules of immunocompetent cells become integral parts of the immunosuppressive therapy. In this study, a mAb against the rat leukocyte common antigen CD45 (RT7) was tested for its immunosuppressive potency after a single perioperative injection.Binding and depleting properties of the anti-RT7 mAb were investigated by flow cytometry. In the fully major histocompatibility complex-disparate heart and skin transplantation models (LEW [RT1l]--LEW.1W [RT1u]), a single dose of anti-RT7 mAb (10 mg/kg) was administered intravenously (day -1). To characterize the long-term acceptance of heart allografts second set skin transplantation (day 100), mixed lymphocyte reaction studies (day 100) and reverse transcriptase-polymerase chain reaction analysis for intragraft cytokine expression (day 200) were performed.The anti-RT7 mAb bound to nearly all hematopoietic lineage cells, but particularly T and NK cells, and profoundly depleted these cells in circulation and lymphoid tissues. Anti-RT7 mAb-treated rats showed long-term acceptance of heart allografts (200 days; n=12), whereas untreated recipients rejected allografts by day 8 (n=6). In contrast to hearts, primary skin allograft survival was only moderately prolonged. Animals with stable heart allograft acceptance showed normal in vitro lymphocyte proliferation responses to donor and third party antigen. These recipients also acutely rejected second set donor-strain skin grafts without inducing rejection of persisting heart allografts. Reverse transcriptase-polymerase chain reaction analysis of intragraft cytokines showed up-regulation of Fas-ligand and IL-4 mRNA in long-surviving heart allografts.The findings demonstrate that a single injection of an anti-RT7 mAb in the rat can induce stable long-term acceptance of heart allografts by transient but profound T-cell depletion. Local immunoregulatory mechanisms seem to play a role for maintenance of long-term graft acceptance.

Hepatic graft reperfusion is associated with inflammatory processes of unknown relevance to the fate of graft. This study aimed to clarify this relevance by histochemical analyses of human hepatic grafts.Paired tissue samples were taken at the end of cold preservation and 2 hr after reperfusion (n=39). From six additional grafts, biopsies were performed at the end of cold preservation only. Injury or inflammatory markers of sinusoidal endothelium (von Willebrand factor-related antigen [vWF]), Kupffer cells (25F9), platelets (CD62), neutrophil leukocytes (CD11b), interleukin (IL)-1beta, intercellular adhesion molecule (ICAM)-1, and HLA-DR were evaluated semiquantitatively by indirect immunoperoxidase staining. Steatosis was also evaluated by hematoxylin and eosin staining.vWF, CD62+ platelet aggregation, CD11b+ leukocytes, and IL-1beta levels increased after reperfusion, and these levels correlated with prereperfusion levels. Not only vWF, CD62+ platelets, CD11b+ leukocytes, IL-1beta, ICAM-1, and steatosis after reperfusion, but also IL-1beta, ICAM-1, and steatosis before reperfusion correlated with postoperative peak transaminase. Furthermore, vWF, CD11b+ leukocytes, 25F9+ macrophages, and ICAM-1 after reperfusion were associated with primary graft nonfunction and strong expressions of ICAM-1 or HLA-DR with early acute rejection. Although some markers (IL-1beta, CD62+ platelets, and CD11b+ leukocytes) correlated with preharvesting parameters (donor age or length of intensive care unit stay), none showed any significant correlation with cold preservation.Synergistic inflammatory events in the hepatic graft at reperfusion, which have a significant impact on the later clinical course, are largely defined and precipitated by injury or activation of nonparenchymal cells preceding reperfusion or even graft harvesting.

Microchimerism has been suggested to play an important role in the long-term acceptance of allogeneic organ grafts by transplant patients and for the maintenance of a state of donor-specific low responsiveness. In order to elucidate the kinetics of the development of chimerism we have performed a follow-up analysis in 10 pediatric patients with living-related liver transplantation (LRLTx). Blood samples obtained during the first 6 months and at 18 months post-transplant and skin biopsies taken at one month were analysed for the presence of donor cells by PCR using donor-specific HLA-DRB1 primer pairs or primers for a Y chromosome-specific sequence. Furthermore 13 long-term patients more than 2 yr after LRLTx were studied at two different time points. In the follow-up studies donor cells could be demonstrated in the blood of all patients immediately after transplantation. After a gradual decline all patients became chimerism-negative for several weeks or months. At 6 months, however, in five of eight patients tested and at 18 months in six of nine patients donor cells had reappeared. This biphasic pattern in the development of chimerism is proposed to reflect the occurrence of different donor-derived cell populations in the recipient. The population giving rise to the first wave of chimerism probably represents matured cells with a limited lifespan which are released from the graft into the circulation of the recipient during the first weeks after transplantation. The population of cells occurring with the second wave of chimerism is likely to have been generated by donor-derived cells with stem cell potential located either in the graft or in the hematopoetic organs of the recipient after emigration from the graft. This model may be able to explain fluctuations in the incidence and degree of microchimerism described in other patient populations during the first year post-transplant. Of the 13 long-term patients, chimerism could be demonstrated in 11. In seven patients it was detected in both blood and skin, in three patients the results obtained for blood and skin were discordant. In one patient only blood was analysed. It is not clear whether the negative results really reflected the absence of chimerism or whether the number of donor cells was below the level of detectability.

The RT6 alloantigenic system of the rat has originally been defined on T lymphocytes of the peripheral lymphatic organs and has been considered to be selectively expressed on mature peripheral T cells. Studying NK cells and intestinal intraepithelial lymphocytes (IEL), we have now found that both cell types also express RT6 and that the expression patterns found for IEL and NK cells were markedly different from each other and also from the expression pattern previously described for T cells of the peripheral lymphatic organs. In lymph nodes, spleen, and blood both RT6- and RT6+ T cells have been found and the density of RT6 expression on the positive cells has been shown to vary over a broad range. In contrast more than 98% of intestinal IEL stained for RT6 and the RT6 density was about tenfold higher than on strongly positive T cells of the peripheral lymphatic organs. Furthermore, the same high RT6 density was also found on IEL of athymic nude rats althogh these cells, to a large extent, lacked other T cell markers. This probably indicates that RT6 expression is an early event in the maturation of intestinal IEL which can occur already before the expression of T cell-specific membrane molecules. The conclusion that the expression of RT6 may be differently regulated in IEL and other T cell populations was further substantiated by the observation that RT6 was also present on IEL of diabetes-prone BB rats which are known to lack RT6 positive T cells in peripheral lymphatic organs. For NK cells still another pattern of RT6 expression was found. Unlike peripheral T cells and IEL, only a small subset of NK cells in blood and spleen expressed RT6. The percentage of RT6 positive cells was increased by in vitro stimulation of isolated NK cells with high concentrations of recombinant rat IL-2 indicating that RT6 expression may be associated with an activated state in NK cells. Taken together, these findings demonstrate that the expression of RT6 is not restricted to T cells and is differently regulated in normal peripheral T cells, intestinal IEL, and NK cells. Since it has recently been demonstrated that the RT6 gene contains two functional promoter regions with major structural disparity it is very likely that the distinct patterns of RT6 expression in different cell types reflect the differential use of the two promoters. The development of this complex control of RT6 expression in evolution may have been driven by a beneficial effect resulting from the use of the RT6 molecular function by several different lymphocyte populations.

The gene products of the RT6 system have been demonstrated to be expressed on the majority of resting peripheral T cells but not on fully activated cytotoxic T cells and in vitro generated long term T cell lines. This has lead to the conclusion that T cell activation causes a loss of RT6 expression. In the present study this question was examined by analysing the expression of RT6 on T cell populations activated in vitro by the T cell mitogen ConA or by allogeneic stimulator cells and subsequently maintained in culture for several weeks. The results showed an initial increase in RT6 expression on most cells during the first two days of culture and a subsequent loss of RT6 expression in many activated cells. Substantial numbers of both CD4+ and CD8+ T cells, however, remained clearly RT6 positive. These cells were present during the entire observation period. The RT6 positive cells did not represent persisting unstimulated cells since they coexpressed CD25 and exhibited typical blast morphology. It is concluded that activation of T cells leads to loss of RT6 expression only in subsets of the CD4 and CD8 T cell populations. The previously reported finding that long term cultures contain only RT6 negative blast cells may indicate preferential survival of RT6 negative blasts rather than obligatory loss of RT6 expression after activation. The possibility is discussed that activated RT6-CD4+ T cells may be inflammatory Th1 cells and activated RT6+CD4+ T lymphoblasts may represent regulatory Th2 cells.

The immunosuppressive effect of a monoclonal antibody (moAb), BT563, directed to the alpha-chain of the IL-2R (CD25), was analyzed in a prospective nonrandomized trial and a prospective randomized trial. Primary objectives were evaluation of the incidence of acute rejections and infections; secondary objectives were safety and tolerability of the moAb. A total of 28 patients were enrolled (phase II) to receive 10 mg/day of BT563 (12 days) as immunoprophylaxis in combination with cyclosporine, azathioprine, and low-dose steroids. Subsequently 32 patients were randomly assigned (phase III) to receive BT563 (10 mg/day) for 12 days or ATG (5 mg/kg/day) for 7 days in addition to cyclosporine and low-dose steroids. No side effects of the BT563 treatment were noted. The actuarial survival was 82% at 12 months in the phase II trial and 92% at 12 months in both arms of the phase III trial. There was one acute rejection in the phase II trial. No acute rejections were noted in the BT arm of the phase III trial and 5 acute rejections were treated in the ATG arm. In the phase II trial 7 infectious episodes were observed, while one infection was seen in the BT arm and 7 in the ATG arm of the triple immunosuppression phase III trial. In all patients circulation of coated CD25+ lymphocytes was observed during BT563 treatment; there was no evidence of depletion or modulation of CD25+ cells. Mean serum levels of BT563 ranged from 1.6 to 7.6 microgram/ml throughout the therapy. An antimurine response was seen in 82% (phase II) and 100% (phase III) of the patients. Antirabbit antibodies were found in 56% of the patients treated with ATG. Analysis of the antimurine response specificity revealed in 56% blocking anti-isotypic antibodies and only in 3% of the patients an anti-idiotypic response. The data of the study presented suggest that therapy with an anti IL-2R moAb is at least equal to ATG application according to the incidence of acute rejections and infections.

Fine-needle aspiration biopsy (FNAB) is a routine diagnostic tool used for the monitoring of the graft during the first postoperative weeks after liver transplantation. The cellular pattern of acute liver rejection is typical in transplant aspiration cytology (TAC), documented and published by several authors. The lymphoid response associated with various viral infections may, however, provide differential diagnostic problems in the cytological monitoring. In this study, we have investigated in detail the cellular pattern of lymphoid response associated with hepatitis C virus (HCV) reactivation, and compared it with the pattern of cytomegalovirus (CMV) infection and with the typical diagnostic findings of acute cellular rejection. HCV reactivation was associated with rather mild total inflammation in the graft (4.5 +/- 1.5 CIU at the peak). The inflammatory infiltrate consisted mainly of small lymphocytes (3.1 +/- 0.2 CIU at the peak), with only occasional activated cells and without lymphoid blast response. No lymphoid activation was seen in the blood. CMV infection was associated with a mild immune response (3.9 +/- 0.4 CIU at the peak) recorded as a slight lymphoid activation and occasional blast cells both in blood and in the graft together with lymphocytosis in the graft (2.4 +/- 0.7 CIU at the peak). The typical findings of acute rejection were easily distinguished from the cellular pictures of both viral infections. The rejections were lymphoid blast (3.6 +/- 3.4 CIU at the peak) and activated lymphocyte (3.5 +/- 2.6 at the peak), dominated by a high peak of total inflammation (9.3 +/- 7.0 CIU). No blast cells and only a few activated cells were seen in the blood during rejection episodes. Thus, the cellular patterns of HCV reactivation and CMV infection differed slightly from each other, but significantly from that of acute liver allograft rejection monitored with the FNAB cytology.

By retrospective analysis of 13,000 blood samples obtained from 248 patients receiving FK 506 therapy, we compared the suitability of plasma with that of whole blood as the matrix for therapeutic drug monitoring of FK 506. The plasma concentrations did not correlate with the concentrations in whole blood (r = 0.56). In contrast to plasma samples (analyzed by enzyme immunoassay), FK 506 was detectable in all whole-blood samples (analyzed by enzyme immunoassay/microparticle enzyme immunoassay). The inter- and intraindividual variations of FK 506 measurements were greater in plasma than in whole blood. Moreover, plasma concentrations correlated only poorly with clinical events. There was a tendency to greater plasma concentrations being measured during episodes of toxicity, but no clear difference was evident between stable course and rejection. In whole-blood specimens, a correlation between reduced or increased FK 506 concentrations and rejection or toxicity, respectively, was observed. The discriminatory power of whole-blood values was greater for the differentiation between toxicity and stable course than between rejection and stable course. We therefore recommend whole blood rather than plasma as the matrix for therapeutic monitoring of FK 506 concentrations.

The cyclosporine (CYA) metabolite patterns in blood were evaluated in patients with liver dysfunction after allogeneic BMT. Fifty-five BMT patients were included in the study until discharge from hospital. Blood trough levels of CYA and 12 of its metabolites were quantified using HPLC. The patients were assigned to three groups: group I (no acute GVHD, n = 23), group II (acute GVHD of the skin and good liver function, overall acute GVHD: grade I: n = 18, grade II: n = 2) and group III (acute GVHD and liver dysfunction, overall acute GVHD: grade II: n = 2, grade III/IV: n = 8). Analysis of the trough blood concentrations of CYA and its metabolites revealed higher concentrations of metabolite AM19 in group III than in the other groups without reaching statistical significance. During acute GVHD of the liver, the metabolites AM19 (p0.01), AM1c9 (p0.05) and AM1A (p0.05) were significantly elevated compared with patients with normal liver function while CYA and all other metabolites did not differ. The CYA metabolite pattern in patients with acute GVHD and liver involvement was identical with that of liver graft patients during acute graft rejection, while the metabolite patterns of the patients without acute GVHD paralleled that of kidney grafted patients with normal liver function. Acute GVHD of the liver leads to an impaired elimination of CYA with increased blood concentrations of single CYA metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

Fifteen young (47-81 days old) and 5 adult (360 days old) Rowett nude rats (rnu/rnu) and 12 euthymic littermates (rnu/+) (56 days old) were infected with Mycoplasma (M.) arthritidis ISR1. The polyarthritis developing after the infection was more severe in the athymic than in the euthymic rats. In the nude rats the disease was progressive and led to the death of 6 animals whereas in the euthymic littermates the disease was resolved within 70 days after infection. In contrast to euthymic rats athymic animals did not develop antibodies against M. arthritidis within 6 weeks (young nude rats) or 23 weeks (adult nude rats) after infection, indicating that M. arthritidis is a thymus dependent antigen. However, low antibody titers were found in the nude rats infected at an age between 47 and 81 days at 340 days after infection, probably due to the development of T-cells which occur in older nude rats. The euthymic as well as the young athymic rats showed an increase in antibody titers after a challenge infection 345 days after the first infection and both were resistant to challenge infection. On the contrary the adult nude rats infected with M. arthritidis did not develop antibodies against the mycoplasmas and were highly susceptible to a second infection after 198 days. This indicates that antibodies play an important role in the defence of the M. arthritidis infection in rats.

Vascular expressed adhesion molecules mediate leukocyte reactivity and activation by receptor-ligand binding. A number of different ligand molecules have been identified to mediate the interaction between endothelial cells and leukocyte subpopulations. In this study, the tissue expression of ELAM-1, CD62 (PADGEM, GMP-140), VACM-1 (INCAM-110), ICAM-2, ICAM-1, and LFA-3 was analyzed on various liver endothelial cell types by immunohistology. The results reveal a differential expression of these molecules in normal liver and inflammation or rejection after liver transplantation. The selectins ELAM-1 and CD62 are basally expressed and inducible on portal tract endothelia (arterial and venous) and central vein endothelia with acute and chronic liver inflammation. Sinusoidal endothelia, however, lack this mechanism, even with severe inflammation, as in cases of irreversible rejection and sepsis. Portal and sinusoidal endothelia show a different expression and inducibility of VCAM-1, ICAM-1, ICAM-2, and LFA-3. The differences in expression of adhesion molecules on liver endothelial cell types may reflect their ability to regulate leukocyte trafficking and activation by means of the expression of specific ligand molecules. The inability of sinusoidal endothelia to express selectins may have implications for the pathophysiology of liver graft infiltration.

Die Kontrolle der immunologischen Abstosung von Organtransplantaten ist neben der Organgewinnung und der Transplantationsoperation die 3. entscheidende Komponente fur den klinischen Behandlungserfolg. Die faszinierende Entwicklung der klinischen Organtransplantation in den letzten 2 Jahrzehnten wurde durch Fortschritte bei der Organisation der Organspende, durch Weiterentwicklungen der chirurgischen Technik und nicht zuletzt wesentliche Fortschritte der Transplantationsimmunologie ermoglicht. Fur die Entwicklung in Hannover war besonders kennzeichnend, das hier seit Beginn der Transplantationstatigkeit innerhalb der Chirurgie der Bearbeitung immunologischer Probleme besondere Bedeutung beigemessen wurde und transplantationsimmunologische Fragestellungen ein wichtiger Schwerpunkt sowohl der klinischen als auch der wissenschaftlichen Arbeit geworden sind. Dies war eine wichtige Basis fur die in den letzten Jahren zunehmend facherubergreifende Bearbeitung von Transplantationsproblemen auch in zahlreichen anderen Bereichen der Medizinischen Hochschule.

The parallel measurement of specific and nonspecific CyA levels by second generation radioimmunoassays based on monoclonal antibodies proved to be an effective procedure to monitor both parent CyA levels and the capacity to eliminate its metabolite. Using this monitoring procedure it could be shown that CyA-associated nephrotoxicity in the early course after liver transplantation is associated with two distinct patterns of blood level derangement. One pattern is characterized by increased parent drug levels, the other by an increased metabolite concentration resulting from severely disturbed CyA metabolite excretion. This raises the possibility that not only the parent drug but also some of its metabolites may exert nephrotoxic effects when present in excessively high concentrations. This finding provided the rationale for a therapeutic CyA-monitoring regimen taking into account both specific and nonspecific measurements. In liver transplant patients monitored according to this regimen and treated with quadruple immunosuppression the incidence and severity of CyA-associated nephrotoxicity was markedly reduced. The metabolite-associated type of nephrotoxicity was only found in patients with severely disturbed liver function.

The commercially available oily solution of ciclosporin which has to be suspended before intake is disliked by some patients for bad taste and has a variable bioavailability. In this investigation the oral pharmacokinetics of ciclosporin and its main metabolites 1 and 17 of the oily solution (Sandimmun) and a soft gelatine capsule preparation of ciclosporin were compared in a crossover fashion in 10 kidney allograft recipients. The results demonstrate a bioequivalence of both formulations. In either case metabolite 17 had a significantly longer half-life than either ciclosporin or metabolite 1. At earlier time-points the concentration of ciclosporin could be best correlated with metabolite 1 and at later time-points with metabolite 17. Both metabolites were less correlated with each other in the late absorption phase of ciclosporin.

Non-invasive measurement of organ blood flow can be achieved by tracing the elimination patterns of 133Xe administered by inhalation. An adaption of the method for the estimation of renal blood flow was developed. The 133Xe is accumulated in the tissue by re-breathing for 1 min and the time course of its washout from the kidney is followed for 14 min thereafter. Normal values were determined in ten dogs and forty-five healthy human volunteers. In man they were similar to results obtained with 131I-hippuran clearance. When flow rates were between 250 and 600 ml/100 g/min the correlation coefficient was 0.84. Only in cases with high cortex flow rates (greater than 600 ml/100 g/min) did the inhalation method give values higher than those determined by the 131I-hippuran clearance. In dogs the results closely correlated with results obtained by direct intra arterial xenon injection (r = 0.96). The value of the inhalation method in routine examination of patients with kidney transplants and its suitability for the early detection of ongoing rejection is demonstrated.

Die intravenose Injektion eines Pferdeantihundelymphocytenserums fuhrt beim Hund zur Verminderung der zirkulierenden Lymphocyten, Granulocyten, Monocyten und Thrombocyten. Die Lymphocytenzahl normalisiert sich langsamer als die der anderen Zellen. Bei wiederholter, taglicher Anwendung des Immunserums in geeigneter Dosierung entwickelt sich eine isolierte, starke und dauerhafte Lymphopenie. Ein Wirkungsverlust des Serums tritt auch bei einer Behandlungszeit von mehreren Monaten nicht auf. Normalpferdeserum fuhrt bei gleicher Dosierung infolge Sensibilisierung des Empfangers zu Schwankungen der Granulocyten und Lymphocyten, jedoch nicht zu dauerhafter Lymphopenie.

Cyclosporin A (CyA) was measured simultaneous in breast milk and maternal and fetal blood with a new monoclonal specific radioimmunoassay in a patient who was treated with Cyclosporin A during pregnancy because of kidney transplantation. CyA-levels in breast milk were 15 to 90% higher than in maternal blood. In case of breast feeding a child would take up less than 5 percent of an immunosuppressive dose. However, we would recommend ablactation because of the toxicity and the unknown side effects of CyA for the child's immunologic system.