Peripheral blood mononuclear cell sonicates as an alternative to irradiated allogeneic cells to stimulate a mixed lymphocyte reaction and to enumerate CD69+ alloreactive T cells.

An alloreactive reaction similar to that occurring during GvHD can be generated in a mixed lymphocyte culture. The presence of both stimulator and responder cells in these cultures makes the identification and enumeration of alloreactive cells difficult and unreliable. We describe the use of PBMC sonicates as an alternative to the standard MLC method to stimulate an allogeneic reaction. Using combinations of autologous or allogeneic PBMC sonicates, we showed that the lymphocyte proliferative response to cell sonicates was comparable to the response using irradiated cells. The proliferative response was concentration dependent and reached maximum levels at day 6. Both irradiated cells and PBMC sonicates induced significantly lower responses when the stimulating cells were partially HLA-DR matched rather than completely mismatched. Alloreactive T cells stimulated with sonicates were enumerated by the flow cytometric detection of CD69 or CD25. In HLA-mismatched cultures, approximately 7% of CD3+ T cells were CD69+ or CD25+, suggesting alloreactivity. Although there was a significant correlation between the expression of these activation markers and lymphocyte proliferative responses, significant individual variations in the results of these two assays were observed. The results in this study demonstrate the potential of using PBMC sonicates instead of irradiated lymphocytes for the study and identification of alloreactive cells at the cellular and molecular level.

Recombinant tissue plasminogen activator (rt-PA) for veno-occlusive liver disease in pediatric autologous bone marrow transplant patients.

The pathogenesis of veno-occlusive disease (VOD) of the liver appears to be secondary to endothelial damage of terminal hepatic venules, which leads to activation of the coagulation cascade, fibrin deposition, and eventual fibrous obliteration of the hepatic venules. Patients with VOD usually present with jaundice, hepatomegaly, weight gain, and ascites. This complication is usually associated with a high mortality rate. We report here the frequency and treatment of VOD in our autologous bone marrow transplant (BMT) patient population. Three of 15 (20%) children (median age 9 years) developed VOD and were treated with recombinant tissue plasminogen activator (rt-PA). Two of these three patients were prepared for BMT with busulfan (16 mg/kg) and cyclophosphamide (Cytoxan, 200 mg/kg), while the other child received cytosine arabinoside (ARA-C 18 g/m2), Cytoxan (3,600 mg/m2) and total body irradiation (TBI, 1,400 y). VOD developed between days 7-24 posttransplant. Clotting studies obtained pretransplant and during VOD included prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, fibrin-degradation product (FDP), proteins C and S, and platelet count. There was no correlation between the incidence of VOD and coagulation status. All patients had normal pretransplant clotting studies. However, protein C levels were noted to be consistently low for those patients at the time of VOD. All three patients received rt-PA at a dose of 0.25-0.5 mg/kg for 4 days. This dose produced increased levels of FDP but did not significantly prolong PT nor PTT. Two of the patients had dramatic responses and had complete resolution of VOD within 6-12 days from the start of therapy. The other patient died of fulminant hepatic failure. It seems that rt-PA is effective in VOD of the liver, which may be associated with low protein C level.

Current treatment and prognosis of Wilms' tumor.

Thanks to the nationally and internationally organized efforts refinements in the therapy of Wilms' tumor have allowed restructuring and reduction of therapeutic strategies. A decrease in tumor relapse and long term sequelae are the immediate goals which will no doubt be the result of tailoring chemotherapy and radiation therapy exposure together with improved surgical techniques and outstanding supportive care.

Wilms' tumor.

In the last 2 decades, important advances in the treatment of Wilms' tumor have been made. The remarkable improvement in survival in these patients has been the product of new surgical techniques, classification of the tumors into prognostic stages upon initial presentation and the tailoring of chemotherapy and radiation therapy thus permitted. A brief historical perspective is presented with a review of the current treatment and ongoing studies.