Joseph J. Goswitz

Prolongation Of Renal Allograft Survival In A Large Animal Model By Oral Rapamycin Monotherapy

We assessed the efficacy of 5 dose levels of oral rapamycin for prolonging renal allograft survival in pigs. Untreated and triple therapy groups (cyclosporine, azathioprine, and prednisone) served as controls. Immunosuppression was administered for 28 days posttransplant and then stopped. Rapamycin whole-blood concentrations were followed weekly. Chemistry, hematology, and lipid values were monitored post-transplant. For rapamycin-treated pigs, median survival time (MST) correlated with both dose and trough levels (ng/ml). All kidneys had some degree of rejection seen on necropsy. After rejection, pneumonia was the most common cause of death. No specific end-organ toxicity was noted on histopathologic examination. Triglyceride and cholesterol levels increased in all treated pigs (both rapamycin and triple therapy) vs. untreated controls--however, all values were within normal limits. Mean ALT levels increased in weeks 2 to 4 in the higher-dose rapamycin groups but returned to baseline in pigs surviving after the drug was stopped. ALT levels did not increase above twice normal in any group. Creatinine levels correlated with the degree of rejection seen on biopsy. We noted no other toxicities. We conclude that rapamycin, given as oral monotherapy, is an effective and safe immunosuppressant in our large animal renal allograft model. Outcome correlated with dose and whole-blood levels.

Beyond hyperacute rejection : accelerated rejection in a discordant xenograft model by adoptive transfer of specific cell subsets

If hyperacute rejection is prevented in the guineapig (GP)-to-Lewis rat (Lew) cardiac xenograft (CXg) model, an accelerated rejection involving cellular infiltration occurs in 3 to 4 days. In previous work using an adoptive transfer model, we found that this accelerated rejection was facilitated by either sensitized splenocytes or sensitized serum. In the current study, in an attempt to determine which splenocyte subset(s) facilitated this process, sensitized splenocytes, with or without subset depletion were injected, into complement- and natural antibody-depleted Lew recipients of GP CXgs. Graft survival was 4.18 +/- 0.75 days with no injection (n = 11), 4.13 +/- 0.99 days with naive splenocytes (n = 8), 1.80 +/- 0.45 days with sensitized splenocytes (n = 5), 2.67 +/- 1.03 days with CD4(W3/25+) depletion of the sensitized splenocytes (n = 6), 3.13 +/- 0.84 days with CD8(OX8+) cell depletion (n = 8), 4.70 +/- 0.68 days with macrophage depletion (n = 10), and 4.22 +/- 0.41 days with B cell depletion (n = 9). Cellular infiltrates, hemorrhage, myocyte necrosis, and endothelial deposition of IgG, IgM, and fibrin were seen in rejected grafts. In most groups, infiltrating cells consisted of CD4 (W3/25+), CD8 (OX8+), IL2R+ cells, macrophages, and natural killer (NK) cells. However, in the macrophages-depleted group, activated (ED2+) macrophages and NK cells were significantly reduced. Total IgM, anti-GP IgM, and anti-GP IgG rebounded in all groups over several days but were not consistent at the time of rejection. Lewis rats rejecting GP CXgs early had lower final titers than those rejecting later. Total IgG titers rebounded to baseline by posttransplant day 1 and were therefore similar in all groups at the time of rejection. These findings suggest that this accelerated rejection requires interaction between macrophages and B cells, since depletion of either significantly alters the rejection tempo. A possible explanation is that xenoreactive IgG antibodies, synthesized by sensitized B cells, bind their target antigens--but also bind sensitized macrophages through their Fc region, thus causing rejection by antibody-dependent cell-mediated cytotoxicity.

Cystoscopic biopsies in pancreaticoduodenal transplantation: Are duodenal biopsies indicative of pancreas dysfunction?

Tissue diagnosis of pancreas graft dysfunction is desirable. Bladder-drained pancreaticoduodenal transplants allow tissue diagnosis by cystoscopic biopsy procedures of the pancreas and duodenum. To assess the diagnostic utility of duodenal biopsies, we reviewed all cystoscopically obtained pancreas and duodenal biopsy tissues at our institution (July 1, 1989 through September 30, 1993). Adequate tissue for histologic examination was obtained from 75 biopsies in 58 recipients. Indications for cystoscopic biopsies were relative hypoamylasuria in 85%, hematuria in 6%, hyperamylasemia in 3%, and other causes in 6%. Duodenal specimens were available from 52 biopsies (25 with, and 27 without, concurrent pancreas biopsies). Of the 27 duodenal biopsies alone, 3 were diagnostic of rejection, 15 had features consistent with rejection, 6 were normal, 1 showed fibrosis, 1 showed necrosis, and 1 was ulcerated. Thus, two-thirds of the duodenal biopsies alone yielded clinically relevant information resulting in antirejection treatment. In 25 of the duodenal biopsies, pancreas tissue was also available (11 simultaneous pancreas-kidney, 9 pancreas transplant alone, and 5 pancreas after kidney recipients). Findings in both organs completely agreed in 9 (36%) of the biopsies. In 7 (28%), rejection was suggested or diagnosed in both organs, although the organs were discrepant with regard to the presence of vascular rejection (6 pancreas, 1 duodenum). In 2 (11%), minor nonrejection discrepant findings were present. Therefore, in 18 of 25 (72%) pancreas-duodenal biopsies, treatment would not have been different if only one graft had been biopsied. But in the other 7 (28%), treatment would have been different if only the organ with negative findings had been biopsied. In 6 cases (4 duodenal, 2 pancreas), rejection was seen in one organ but not the other. In 1 case, cyto-megalovirus (CMV) inclusions were present in the duodenum, but the pancreas was normal. We conclude that (1) the duodenum and pancreas can reject inde-

Testicular Sex Cord-Stromal Tumors in Children: Clinicopathologic Study of Sixteen Children with Review of the Literature

Sex cord-stromal tumors of the pediatric testis present diagnostic and therapeutic challenges. This study examines the clinicopathologic features of 16 testicular sex cord-stromal tumors from children less than 18 years of age. Four juvenile granulosa cell tumors and five tumors of Sertoli or incomplete differentiation in this study had high mitotic rates and/or sarcomatoid areas that suggested malignancy, but none of these children developed recurrence or metastases. Some of these tumors had been initially misdiagnosed as yolk sac tumors or rhabdomyosarcomas because of the presence of areas superficially resembling these neoplasms. These morphologic pitfalls have received little attention in the literature. Even incompletely differentiated sex cord-stromal tumors have at least focal areas characteristic of juvenile granulosa or Sertoli cell differentiation. In addition, immunohistochemical negativity for alpha-fetoprotein, muscle specific actin, and desmin are useful for ruling out yolk sac tumor and rhabdomyosarcoma. Four patients had Leydig cell tumors and three had large cell calcifying Sertoli cell tumors. Children with Leydig cell tumors are not at risk for metastasis, but children with large cell calcifying Sertoli cell tumors are at risk for endocrine syndromes as illustrated by one of our cases. The differential diagnosis of these tumors is also discussed.

Synovial sarcoma. Large size predicts poor outcome.

A consecutive series of 38 patients with synovial sarcoma diagnosed and treated in a consistent fashion from 1976 to 1994 was reviewed for prognostic variables. The histologic specimens were reviewed and confirmed by one pathologist. There was a minimum 4-year followup for all surviving patients and no patients were lost to followup. The treatment protocol consisted of surgical excision with a wide or radical margin and limb preservation when possible. In those patients in whom the surgical margin was undefined or was less than a wide margin, perioperative radiation therapy was used. Four patients presented with metastatic disease and all died of their disease. Thirty-four patients had localized disease at presentation. Variables considered in stratifying outcomes included histologic grade, histologic subtype, surgical margin, presence or absence of local recurrence, age, and size of tumor. Of the 34 patients without metastasis there was a strong statistical association between size of tumor and survival: 17 patients with tumors less than 5 cm indiameter had a 100% survival, 12 patients with tumors 5 cm to 10 cm had a 75% survival, and five patients with tumors greater than 10 cm had a 20% survival. The authors urge that a multicenter trial for neoadjuvant chemotherapy be initiated for patients presenting with a synovial sarcoma greater than 10 cm in diameter.

The role of monocytes and macrophages in delayed xenograft rejection

Abstract: Despite the development of successful strategies for averting hyperacute rejection (HAR) in both small and large animal xenograft models, a delayed xenograft rejection (DXR) ultimately occurs. This process is characterized by endothelial cell activation and graft infiltration with activated monocytes and natural killer (NK) cells. We evaluated the role of monocytes and macrophages in a guinea pig‐to‐rat model of DXR. Our results suggest that specific interactions between these cells and the xenograft occur that result in their activation, since adoptive transfer of xenoactivated splenocytes significantly accelerated both DXR and allograft rejection, while adoptive transfer of alloactivated splenocytes did not. Furthermore, while normal splenocytes caused antibody‐dependent cell‐mediated cytotoxicity (ADCC) of xenogeneic endothelial cells, xenoactivated splenocytes caused significantly greater endothelial cytotoxicity by antibody‐independent mechanisms. Both normal and xenoactivated splenocytes were significantly less cytotoxic if adherent cells, consisting predominantly of monocytes and macrophages, were first removed. In vivo recipient macrophage depletion, using liposome‐encapsulated dichloromethylene diphosphonate, did not influence DXR and this may indicate that nonphagocytic circulating monocytes may be more important in DXR. However, adoptive transfer of splenocytes from a macrophage depleted, xenoactivated donor did not accelerate xenograft rejection, while splenocytes from a nondepleted xenoactivated donor did, thereby supporting the importance of monocytes and macrophages in this I phase of xenograft rejection.

Lipoblastoma of the foot

Abstract Lipoblastoma is an uncommon benign lipomatous soft tissue mass of childhood, occurring most commonly in children less than 3 years of age. We present a case of lipoblastoma occurring in the foot of a 14-year-old boy and review the literature. The appearance of the mass on magnetic resonance imaging (MRI) is illustrated and is correlated with the findings at gross and microscopic pathological examination. A lobulated architecture, the presence of adipose tissue, thin nonenhancing septa, peripheral lobules of more immature and therefore less specific tissue, and a peripheral pseudocapsule were evident on MRI and at pathological examination.

Case report 853

Fig. 2. A Posteroanterior and B lateral radiographs of the chest (March 1992). A small right hilar nodule is indicated by the arrow. The thoracic spine appears normal Fig. 3. A Posterior and B lateral radiographs of the chest (April 1992). A small right hilar nodule is again noted. New collapse of the T6 vertebral body is demonstrated Fig. 4. Tl-weighted sagittal MRI of thoracic spine, showing replacement of normal signal marrow signal and collapse of the T6 vertebral body. A mass is seen to extend out of the vertebral body Clinical information