Expression of the innate defense receptor S5D-SRCRB in the urogenital tract.

S5D-SRCRB is a novel mouse secretory glycoprotein belonging to the ancient and highly conserved scavenger receptor cysteine-rich superfamily of protein receptors. Available evidence indicates that S5D-SRCRB interacts with conserved microbial cell wall components, as well as with some endogenous proteins, and presents a restricted tissue expression pattern. This study further analyzes the expression of S5D-SRCRB along the mouse urogenital tract. Immunohistochemical staining for S5D-SRCRB was observed in spermatocytes from seminiferous tubules and in the epithelial surface from urethra and bladder, as well as in kidney tubules, mainly from medulla and papilla. Double stainings showed that S5D-SRCRB is expressed in both principal (P) and intercalated (IC) cells from renal collecting ducts (CD). By using an in vitro cell model of IC cell differentiation, preferential expression of S5D-SRCRB was observed in the apical border of terminally differentiated IC. Colocalization of S5D-SRCRB with galectin-3 (Gal-3) was also observed in kidney and bladder, but not in testis, supporting concurrent biochemical studies demonstrating the carbohydrate-dependent interaction of Gal-3 and S5D-SRCRB. Furthermore, upregulation of S5D-SRCRB expression was observed in in vitro and in vivo models of bacterial aggression, reinforcing the emerging view that CD, and specially IC, are important players in innate defense of the urinary tract against infection. Taken together, the results indicate that S5D-SRCRB is an integral component of the urogenital tract involved in innate immune functions.

Accommodation of vascularized xenografts: expression of "protective genes" by donor endothelial cells in a host Th2 cytokine environment.

Organ xenografts under certain circumstances survive in the presence of anti-graft antibodies and complement, a situation referred to as "accommodation." We find that the endothelial cells (ECs) in hamster hearts that accommodate themselves in rats express genes, such as A20 and bcl-2, that in vitro protect ECs from apoptosis and prevent upregulation in those cells of proinflammatory genes such as cytokines, procoagulant and adhesion molecules. Hearts that are rejected do not express these genes. In addition, vessels of rejected hearts show florid transplant arteriosclerosis whereas those of accommodated hearts do not. Accommodated xenografts have an ongoing T helper cell type 2 (Th2) cytokine immune response, whereas the rejected grafts have a Th1 response. We propose a model for factors that contribute to the survival of xenografts and the avoidance of transplant arteriosclerosis.

A20 inhibits cytokine-induced apoptosis and nuclear factor kappaB-dependent gene activation in islets.

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease resulting from apoptotic destruction of beta cells in the islets of Langerhans. Low expression of antioxidants and a predilection to produce nitric oxide (NO) have been shown to underscore beta cell apoptosis. With this perspective in mind, we questioned whether beta cells could mount an induced protective response to inflammation. Here we show that human and rat islets can be induced to rapidly express the antiapoptotic gene A20 after interleukin (IL)-1beta activation. Overexpression of A20 by means of adenovirus-mediated gene transfer protects islets from IL-1beta and interferon gamma-induced apoptosis. The cytoprotective effect of A20 against apoptosis correlates with and is dependent on the abrogation of cytokine-induced NO production. The inhibitory effect of A20 on cytokine-stimulated NO production is due to transcriptional blockade of inducible NO synthase (iNOS) induction; A20 inhibits the activation of the transcription factor nuclear factor kappaB at a level upstream of IkappaBalpha degradation. These data demonstrate a dual antiapoptotic and antiinflammatory function for A20 in beta cells. This qualifies A20 as part of the physiological cytoprotective response of islets. We propose that A20 may have therapeutic potential as a gene therapy candidate to achieve successful islet transplantation and the cure of IDDM.

Anti-tumor necrosis factor modulates anti-CD3-triggered T cell cytokine gene expression in vivo.

De novo expression of TNF, IFN gamma, IL-3, IL-4, and IL-6 genes was initiated rapidly by treatment of mice with anti-CD3. A specific feature of this reaction was that TNF was derived exclusively from T cells. TNF was produced both as a mature soluble trimeric protein and as a 26-kD anti-TNF-reactive protein compatible with membrane-anchored TNF. Pretreatment with anti-TNF did not affect anti-CD3-triggered TNF mRNA expression in T cells. In contrast, in vivo and in vitro anti-TNF treatment upregulated anti-CD3-induced IFN gamma mRNA expression and inhibited IL-4 mRNA expression. These latter effects were not dependent on TNF neutralization: pretreatment with soluble recombinant 55-kD TNF receptor (TBPI) as an alternative TNF-neutralizing agent did not modify the anti-CD3-induced cytokine profile. These results suggest that a direct interaction between anti-TNF and T cell membrane-anchored TNF could account for the observed modulation of cytokine gene expression. The increased expression of INF gamma mRNA observed in anti-TNF-treated animals correlated with a decrease in IL-3 and IL-6 mRNA expression. Conversely, IFN gamma blockade by a neutralizing anti-IFN gamma mAb led to a substantial increase in both IL-3 and IL-6 gene expression induced by anti-CD3. Taken together, these results strongly argue for the existence, in the anti-CD3-induced cytokine cascade, of IFN gamma-dependent regulation of IL-3 production, which in turn modulates IL-6 production.

Bcl-2 and Bcl-XL serve an anti-inflammatory function in endothelial cells through inhibition of NF-kappaB.

To maintain the integrity of the vascular barrier, endothelial cells (EC) are resistant to cell death. The molecular basis of this resistance may be explained by the function of antiapoptotic genes such as bcl family members. Overexpression of Bcl-2 or Bcl-XL protects EC from tumor necrosis factor (TNF)-mediated apoptosis. In addition, Bcl-2 or Bcl-XL inhibits activation of NF-kappaB and thus upregulation of proinflammatory genes. Bcl-2-mediated inhibition of NF-kappaB in EC occurs upstream of IkappaBalpha degradation without affecting p65-mediated transactivation. Overexpression of bcl genes in EC does not affect other transcription factors. Using deletion mutants of Bcl-2, the NF-kappaB inhibitory function of Bcl-2 was mapped to bcl homology domains BH2 and BH4, whereas all BH domains were required for the antiapoptotic function. These data suggest that Bcl-2 and Bcl-XL belong to a cytoprotective response that counteracts proapoptotic and proinflammatory insults and restores the physiological anti-inflammatory phenotype to the EC. By inhibiting NF-kappaB without sensitizing the cells (as with IkappaBalpha) to TNF-mediated apoptosis, Bcl-2 and Bcl-XL are prime candidates for genetic engineering of EC in pathological conditions where EC loss and unfettered activation are undesirable.

The universal NF-kappaB inhibitor a20 protects from transplant vasculopathy by differentially affecting apoptosis in endothelial and smooth muscle cells.

Transplant vasculopathy (TV) is an accelerated form of atherosclerosis resulting in chronic rejection of vascularized allografts. The causes of TV are multifactorial and integrate at the level of the vascular wall, leading to a phenotypic switch of endothelial cells (ECs) and smooth muscle cells (SMCs). A20 is a NF-kappaB-dependent stress response gene in ECs and SMCs with potent anti-inflammatory effect in both cell types through blockade of NF-kappaB. A20 expression in ECs and SMCs correlates with the absence of TV in rat kidney allografts and long-term functioning human kidney allografts. We demonstrate that A20 protects ECs from tumor necrosis factor, Fas, and natural killer cell-mediated apoptosis by inhibiting proteolytic cleavage of caspase 8. A20 also safeguards ECs from complement-mediated necrosis. Hence, effectively shutting down cell death pathways initiated by inflammatory and immune offenders associated with TV. In contrast, A20 sensitizes SMCs to cytokine and Fas-mediated apoptosis through a novel nitric oxide (NO)-dependent mechanism. The unexpected proapoptotic effect of A20 in SMCs translates in vivo by the regression of established neointimal carotid lesions following balloon angioplasty in rats. Antedating apoptosis of SMCs, expression of the inducible NO synthase increases in A20-expressing neointimal SMCs, corroborating the involvement of NO in causing the proapoptotic effect of A20 in SMCs. Combined anti-inflammatory and anti- or proapoptotic functions of A20 in ECs and SMCs respectively qualify the positive effect of A20 upon vascular remodeling and healing. We propose that A20-based therapies may be effective in prevention and treatment of TV.

Significant lethality following liver resection in A20 heterozygous knockout mice uncovers a key role for A20 in liver regeneration.

Hepatic expression of A20, including in hepatocytes, increases in response to injury, inflammation and resection. This increase likely serves a hepatoprotective purpose. The characteristic unfettered liver inflammation and necrosis in A20 knockout mice established physiologic upregulation of A20 as integral to the anti-inflammatory and anti-apoptotic armamentarium of hepatocytes. However, the implication of physiologic upregulation of A20 in modulating hepatocytes' proliferative responses following liver resection remains controversial. To resolve the impact of A20 on hepatocyte proliferation and the liver's regenerative capacity, we examined whether decreased A20 expression, as in A20 heterozygous knockout mice, affects outcome following two-third partial hepatectomy. A20 heterozygous mice do not demonstrate a striking liver phenotype, indicating that their A20 expression levels are still sufficient to contain inflammation and cell death at baseline. However, usually benign partial hepatectomy provoked a staggering lethality (>40%) in these mice, uncovering an unsuspected phenotype. Heightened lethality in A20 heterozygous mice following partial hepatectomy resulted from impaired hepatocyte proliferation due to heightened levels of cyclin-dependent kinase inhibitor, p21, and deficient upregulation of cyclins D1, E and A, in the context of worsened liver steatosis. A20 heterozygous knockout minimally affected baseline liver transcriptome, mostly circadian rhythm genes. Nevertheless, this caused differential expression of >1000 genes post hepatectomy, hindering lipid metabolism, bile acid biosynthesis, insulin signaling and cell cycle, all critical cellular processes for liver regeneration. These results demonstrate that mere reduction of A20 levels causes worse outcome post hepatectomy than full knockout of bona fide liver pro-regenerative players such as IL-6, clearly ascertaining A20's primordial role in enabling liver regeneration. Clinical implications of these data are of utmost importance as they caution safety of extensive hepatectomy for donation or tumor in carriers of A20/TNFAIP3 single nucleotide polymorphisms alleles that decrease A20 expression or function, and prompt the development of A20-based liver pro-regenerative therapies.

Corticosteroid inhibition of the OKT3-induced cytokine-related syndrome--dosage and kinetics prerequisites.

The data presented extend to a larger series of 27 consecutive renal allograft recipients treated prophylactically with OKT3 our previous observation that the acute OKT3-induced clinical syndrome is related to massive release in the circulation of some cytokines, among which are tumor necrosis factor and interferon gamma. In addition, a pilot randomized study was set up including 12 consecutive patients receiving high-dose corticosteroid treatment (0.5 g solumedrol) either before or at the same time as the first OKT3 injection. Results confirm that when corticosteroids are given in sufficient amount and, importantly, 1 hr before the first OKT3 injection, they significantly decrease the release of both tumor necrosis factor and interferon gamma. In addition, the pretreatment with corticosteroids may totally abolish the IL-2 release induced by OKT3. Given the key role the massive although transient cytokine release plays in determining the OKT3-induced acute syndrome, these results provide the biological basis supporting a precise kinetics of administration of high-dose corticosteroids to better decrease the severity of the clinical reaction.

Membrane-associated lymphotoxin on natural killer cells activates endothelial cells via an NF-kappaB-dependent pathway.

BACKGROUND: Inhibition of complement in small animal models of xenotransplantation has demonstrated graft infiltration with natural killer (NK) cells and monocytes associated with endothelial cell (EC) activation. We have previously demonstrated that human NK cells activate porcine EC in vitro, which results in adhesion molecule expression and cytokine secretion. In this study, we used the NK cell line NK92 to define the molecular and cellular basis of NK cell-mediated EC activation. METHODS: EC were transfected with either reporter constructs containing the luciferase gene driven either by E-selectin or interleukin (IL)-8 promoters or a synthetic NF-kappaB-dependent promoter. In addition, a dominant-negative mutant tumor necrosis factor receptor I (TNFRI) expression vector was co-transfected in inhibition studies. Forty-eight hours after transfection, EC were stimulated with NK cells or NK cell membrane extracts for 7 hr and activation was measured by a luciferase assay. RESULTS: Co-culture of NK cells with transfected EC enhanced E-selectin, IL-8, and NF-kappaB-dependent promoter activity. NK cell membrane extracts retained the capacity to activate EC and induced nuclear translocation of NF-kappaB (p50 and p65). Western blotting of NK cell and membrane extracts detected the presence of Lymphotoxin-alpha (LTalpha) but not tumor necrosis factor-alpha. Furthermore, LTalpha was secreted in NK:EC co-cultures. Co-transfection with dominant-negative mutant TNFRI inhibited EC activation by NK cell membrane extracts and by NK cells by 80% and 47%, respectively. The same pattern of inhibition was observed using anti-human LT sera. CONCLUSIONS: Human NK cell membrane-bound LT signals across species via TNFRI, leading to NF-kappaB nuclear translocation and transcription of E-selectin and IL-8, which results in EC activation. The discrepancy in the degree of inhibition by membrane extracts and NK cells with mutant TNFRI suggests that additional pathways are utilized by NK cells to activate EC.

Human monocytes activate porcine endothelial cells, resulting in increased E-selectin, interleukin-8, monocyte chemotactic protein-1, and plasminogen activator inhibitor-type-1 expression.

Monocytes (Mo) are thought to be important effector cells in early xenograft rejection. Effects of Mo-endothelial cell (EC) interactions on EC activation in vitro were studied by coculturing human Mo or human monocytoid cell lines, U937 and THP-1, with porcine EC. Without preactivation, U937 cells and Mo induced mRNA for the EC-specific adhesion receptor, E-selectin, expressed only on activated cells, after 2 hr. Surface protein was maximal when equal numbers of EC and Mo were cocultured. Increased mRNA expression of the chemokines, interleukin-8 and monocyte chemotactic protein-1, and the antifibrinolytic protein plasminogen activator inhibitor type-1, confirmed EC activation. Like E-selectin, plasminogen activator inhibitor type-1 mRNA was rapidly induced and returned to baseline after 24 hr, whereas chemokine gene expression was slower and more prolonged. Interleukin-1 receptor antagonist failed to modulate induction of E-selectin. Soluble tumor necrosis factor (TNF) alpha receptor inhibited E-selectin induced by TNF alpha, but not by U937 cells, and mRNA and protein on EC in Mo-EC mixtures cocultured at 1:1 ratios were not significantly reduced. The TNF alpha inhibitor did reduce E-selectin expression (30-40%), as well as induced chemokine gene expression (80%), at higher Mo-EC ratios. Despite this, minimal TNF alpha was detectable in supernatants. These results, along with the transwell experiments that confirmed a requirement for Mo-EC contact, suggest that membrane-bound TNF alpha may be involved. Thus, Mo-EC interactions in the porcine to human combination activated several EC functions, suggesting that initial Mo contact with the vessel wall of a xenogeneic graft may promote leukocyte recruitment, inflammation, and maintenance of thrombus, resulting in eventual organ destruction.

Epstein-Barr virus infection is associated with endothelial Bcl-2 expression in transplant liver allografts.

INTRODUCTION: In liver transplant recipients with Epstein-Barr virus (EBV) disease, we reported a low rate of acute rejection after stopping or markedly lowering immunosuppression. This observation led to the hypothesis that EBV, as a means of viral persistence, induces expression of antiapoptotic factors and these factors, in turn, confer protection to the transplanted organ. Bcl-2, an antiapoptotic factor induced by EBV in various host cells, is not normally expressed in the liver. We questioned whether bcl-2 is expressed in the transplanted liver and whether its expression is modified by EBV. MATERIALS AND METHODS: Retrospective liver biopsy specimen from liver transplant patients diagnosed with EBV (n=12) were examined for the presence of bcl-2 by immunohistochemistry and compared with EBV (-) transplant (n=15), and nontransplant (n=13) livers. RESULTS: The most significant finding was the presence of endothelial bcl-2 expression in the majority of EBV (+) transplant samples examined (67%) and its relative absence in the other two groups (P<0.005). There was also bcl-2 expression in the hepatocytes and lymphocytes of the majority of transplant liver samples, irrespective of EBV status. DISCUSSION: We have identified a strong association between EBV infection and endothelial bcl-2 expression in transplant livers. We also found that transplantation, in itself, was associated with bcl-2 expression in the hepatocytes and lymphocytes of liver allografts.

Implications of de novo ELAM-1 and VCAM-1 expression in human cardiac allograft rejection.

Both cytokines produced by activated monocytes and T cells and direct cell-to-cell contact with antigen-primed T cells during inflammatory reactions are known to induce the expression of several adhesion proteins on endothelial cells. In this prospective longitudinal study, we analyzed the expression of ELAM-1, VCAM-1, and ICAM-1 on myocardial allograft biopsy specimens taken from 16 cardiac allograft recipients either for routine monitoring or for the investigation of suspected rejection. Infiltrating T cells were identified using anti-CD3 antibodies. Three to six sequential biopsies taken at one-week intervals were analyzed by means of conventional histology and immunohistochemistry. Seven patients did not develop rejection during the study; their biopsies were negative for VCAM-1 and ELAM-1, although faint ICAM-1 staining was present on capillaries, reflecting constitutive expression. Three patients entered the study with clear-cut clinical and histologic signs of acute rejection. Intense VCAM-1 and ICAM-1 expression was detected on capillary and postcapillary venules, together with a heavy CD3+ T cell infiltrate; VCAM-1 was also expressed on arteriolar endothelial cells. ELAM-1 was undetectable in all three cases. Six patients developed acute rejection during the course of the study. In four, ELAM-1 and VCAM-1 were expressed on both capillary and postcapillary venules one or two weeks before the histological diagnosis of rejection (heavy CD3+ cell infiltrate). Importantly, ELAM-1 expression was short-lived and had disappeared by the time CD3+ cellular infiltrate was detected, thus extending in vivo the finding that ELAM-1 expression is usually transient in vitro. Only VCAM-1 expression was observed in the other two patients, one week prior to the histological diagnosis of rejection. These results suggest that ELAM-1 and VCAM-1 might represent early predictive markers of acute cardiac allograft rejection. ELAM-1 expression is, however, usually transient, necessitating frequent testing.

In vivo cell activation following OKT3 administration. Systemic cytokine release and modulation by corticosteroids.

A massive and self-limited release of tumor necrosis factor and interferon gamma was detected in the systemic circulation in 35 consecutive renal allograft recipients by specific radioimmunoassays very soon following the first injection of the monoclonal antibody OKT3 (anti-CD3). Peak serum TNF and IFN gamma levels were reached, respectively, at 1 and 4 hr following the first OKT3 injection. Abnormally high serum interleukin 2 levels were also observed 4 hr following the first OKT3 injection in a minority of patients (5 cases). OKT3 had no effect on interleukin 1 beta, interferon alpha, and granulocyte/macrophage colony stimulating factor serum levels, which in all patients remained within the normal range throughout the study. This selective OKT3-induced cytokine release, which only followed the first injection, was transient (i.e., lasting a few hours). It tightly paralleled the spontaneously reversible clinical syndrome characterized by high fever, headaches, and gastrointestinal symptoms that is invariably associated with the first OKT3 administration. Importantly, when administered in adequate dosages and with adequate timing, corticosteroids influenced both the cytokine release and the systemic reaction. Thus, the highest TNF, IFN gamma, and IL-2 serum levels were detected in patients who did not receive corticosteroids. Patients who received high-dose corticosteroids (1 g solumedrol bolus) concomitantly with the first OKT3 injection still had high TNF and IFN gamma levels. Conversely, when the same corticosteroid dose was injected 15-60 min prior to the first OKT3 injection, in all cases the increase of serum TNF and IFN gamma was significantly lower as compared with the above-described groups; IL-2 levels did not rise. These data offer a direct explanation for one major side effect of OKT3 and thus provide the basis for devising means to prevent its occurrence.

Reduction of morbidity and cytokine release in anti-CD3 MoAb-treated mice by corticosteroids.

In keeping with the in vitro mitogenic properties of anti-CD3 MoAbs, the first injections of anti-CD3 are invariably responsible for an in vivo cellular activation. This activation induces a massive cytokine release in the circulation (TNF, IFN gamma, IL-2, IL-6, and IL-3). Paralleling this release, a severe clinical reaction occurs in OKT3-treated patients and in 145 2C11-treated mice. Corticosteroids both in vitro and in vivo inhibit the production of several cytokines involved in the anti-CD3 reaction. A single 1 mg hydrocortisone dose was administered to 145 2C11-treated mice according to different kinetics schedules. When given 1 hr prior to the anti-CD3 MoAb, hydrocortisone exerted a beneficial effect on the mouse physical reaction. Hypothermia was totally abrogated at the 4-hr time point. Diarrhea decreased by 50%. Hypomotility improved although not significantly. This improvement correlated with a major modification in the anti-CD3 pattern of cytokine release. At the 90-min blood withdrawal time point cytokine serum levels showed a 100% decrease for IFN gamma, an 88% decrease for IL-6, and 85% decrease for IL-2, and a 75% decrease for TNF. At 4 hr IL-2 serum levels were diminished by 65%; IL-6, IL-3, and IFN gamma serum levels were comparable to controls; and, interestingly, TNF was still detected, whereas it has already disappeared when 145 2C11 was administered alone. Importantly, when given more than 1 hr prior to anti-CD3 injection, corticosteroids were ineffective. To conclude, high doses of corticosteroids must be given with a precise kinetics--i.e. 1 hr prior to anti-CD3 MoAb--to achieve their maximal beneficial effect in the prevention of the anti-CD3 reaction.

Evidence that antihuman tumor necrosis factor monoclonal antibody prevents OKT3-induced acute syndrome.

We have used an antihuman tumor necrosis factor monoclonal antibody, CB006 (murine IgG1), to prevent the OKT3-induced acute clinical syndrome. This syndrome is due to the massive, although transient release in the circulation of various cytokines (TNF, interferon gamma, interleukin 2, interleukin 6) and represents one important side effect linked to in vivo use of OKT3. Fourteen kidney allograft recipients undergoing prophylactic OKT3 therapy were treated with CB006 in a single i.v. injection of either 0.4 mg/kg (group I, 7 patients) or 2 mg/kg (group II, 7 patients), 1 hr before the first OKT3 administration. Nineteen consecutive patients formed a historical control group. None of the CB006-pretreated patients showed any of the common, severe OKT3-associated symptoms (hypotension, respiratory distress, or neurotoxicity), which were observed in 10% of the historical controls. In addition, CB006-treated patients showed a lower frequency of pyrexia (> or = 39 degrees C) and gastrointestinal symptoms. None of the CB006-treated patients presented severe vomiting or diarrhea, defined as repeated episodes inducing significant fluid and electrolyte loss. Two out of the 7 patients in group I and group II had mild transitory diarrhea. Mild single vomiting episodes occurred in 2 group I patients and 3 group II patients. At variance in all controls, gastrointestinal symptoms were long lasting and associated with major prostration due to electrolyte and fluid loss. Importantly, CB006-treated patients who presented mild symptoms had detectable bioactive circulating TNF, showing incomplete inactivation of OKT3-induced TNF by CB006. CB006 was perfectly well tolerated, did not induce xenosensitization, and did not affect the biological or clinical effectiveness of OKT3.

Expression of adhesion molecules in 113 patients with B-cell chronic lymphocytic leukemia: relationship with clinico-prognostic features.

The B-cell chronic lymphocytic leukemia (B-CLL) is a heterogeneous disease, its clinical and biological behavior possibly being influenced by surface molecules expressed in B-lymphocytes. These molecules mediate cell adhesion, mobility and homing. Expression of surface adhesion molecules of the integrin family (CD11a/CD18 or LFA-1, CD11c/CD18), of the immunoglobulin-related family (CD54), of the selectin family (CD62L or LAM-1) and the lymphocyte homing receptor (CD44) were analyzed in peripheral cells from 113 B-CLL patients. The association with three prognosis-related parameters (Rai stage, bone marrow pattern and doubling time) was determined. The study included only patients with B-CLL lymphocytes of typical morphology, which always expressed CD5 and CD23. Low expression of integrins, particularly CD18, was associated with advanced disease (Rai stages III-IV) and diffuse bone marrow pattern, even after adjusting for other prognosis-related variables. Expression of CD54 was associated independently with rapid doubling time (less than 12 months). The association persisted after adjusting for stage and bone marrow pattern; CD44 was expressed in all patients. No correlations were found between expression of CD62L and the prognostic variables analyzed. In conclusion, CD54 expression and low CD18 expression are both significantly associated with poor prognostic features.

Henoch-Schönlein purpura as clinical presentation of a myelodysplastic syndrome.

Small-vessel vasculitis may be a paraneoplastic syndrome. It may be associated with haematologic malignancies and less frequently with solid tumors. We describe a patient with myelodysplastic syndrome presenting as Henoch-Schönlein Purpura. To our knowledge this association has not previously reported.

[Acute clinical syndrome associated with OKT3 administration. Prevention by single injection of an anti-human TNF monoclonal antibody]. / Syndrome clinique aigu lié à l'administration d'OKT3. Prévention par une injection unique d'un anticorps monoclonal anti-TNF humain.

This study analyzed the capacity of an anti-human tumour necrosis factor (TNF) monoclonal antibody, CB006 (murine IgG1, Celltech), to prevent the OKT3-induced acute clinical syndrome. Fourteen renal allograft recipients undergoing prophylactic OKT3 therapy were included. CB006 was administered as a single i.v. injection, 0.4 mg/kg (Group I, 7 patients) and 2 mg/kg (Group II, 7 patients), one hour prior to the first OKT3 administration. Nineteen consecutive patients that were part of a randomized multicenter trial constituted the historical control group. In all patients CB006 was perfectly well tolerated and significantly decreased the frequency of the common OKT3-associated acute symptoms. None of the CB006 pretreated patients showed severe life threatening symptoms (hypotension, respiratory distress or neurotoxicity), observed in 10 per cent of historical controls. At variance with controls, in CB006 treated patients gastrointestinal symptoms (vomiting, diarrhea) and pyrexia (body temperature greater than or equal to 39 degrees C) appeared in low frequency, were mild and short lasting, never promoting major prostration of the patients due to electrolytes and fluid loss. Importantly, the presence in some patients of these mild symptoms, correlated with detectable bioactive TNF in the circulation thus reflecting incomplete blockade by CB006 of OKT3-induced TNF. CB006 pharmacokinetics data further stressed the need for adequate dosage adaptation. CB006 did not affect the biological or clinical effectiveness of OKT3. None of the patients showed evidence of anti-CB006 xeno-sensitization.