RESUMEN
A general hindrance to progress in adoptive cellular therapy is the lack of detailed knowledge of the fate of transferred cells in the body of the recipient. In this study, we present a novel technique for tracking of 124I-labeled cells in situ, which combines the high spatial resolution of magnetic resonance imaging with the high sensitivity and spatial accuracy of positron emission tomography. We have used this technique, together with determination of tissue radioactivity, flow cytometry, and microscopy, to characterize and quantitate the specific accumulation of transferred CD8+ T cells in tumor tissue in a mouse model. Transgenic CD8+ T cells, specific for the ovalbumin peptide SIINFEKL, were adoptively transferred to recipients carrying a subcutaneous tumor of the ovalbumin-expressing malignant melanoma cell line B16-OVA. The number of SIINFEKL-specific CD8+ cells in the tumor tissue was determined by flow cytometry each day for 8 consecutive days after adoptive transfer. From low levels 1 day after injection, their number gradually increased until day 5 when an average of 3.3x10(6) SIINFEKL-specific cells per gram tumor tissue was found. By applying the combined positron emission tomography/magnetic resonance imaging technique we were able to determine the position of the transferred, 124I-labeled SIINFEKL-specific T cells in 3 dimensions in recipient mice, and could demonstrate a highly significant accumulation of the 124I label in and around the subcutaneous B16-OVA tumors compared with normal tissue. Accumulation of 124I was significantly higher in B16-OVA than in B16 tumors not expressing the OVA antigen.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Inmunoterapia Adoptiva/métodos , Melanoma Experimental/inmunología , Receptores Mensajeros de Linfocitos/inmunología , Animales , Proteínas del Huevo/inmunología , Femenino , Radioisótopos de Yodo , Imagen por Resonancia Magnética , Masculino , Melanoma Experimental/diagnóstico por imagen , Melanoma Experimental/patología , Ratones , Ratones Endogámicos C57BL , Ovalbúmina/inmunología , Fragmentos de Péptidos , Tomografía de Emisión de PositronesRESUMEN
OBJECTIVE: Cardiac surgery with cardiopulmonary bypass elicits a systemic inflammatory response. An exaggerated response is associated with organ dysfunction and increased morbidity and mortality. DESIGN: The aim of the present study was to investigate whether the cardiopulmonary bypass procedure in itself results in accumulation of isotope-labeled platelets, polymorphonuclear neutrophils, and fibrinogen at organ levels in neonatal pigs and to monitor changes in organ function. SETTING: Pediatric cardiopulmonary bypass setup with 60 mins of aortic cross-clamp time and 120 mins of hypothermic cardiopulmonary bypass time. SUBJECTS: Thirty piglets were allocated to sternotomy alone (sham group, n = 15) or to sternotomy and cardiopulmonary bypass (n = 15). MEASUREMENTS AND MAIN RESULTS: Isotope-labeled autologous polymorphonuclear neutrophils, platelets, and commercially available fibrinogen were infused, and the specific accumulation at organ level was measured in a gamma counter 4 hrs after termination of cardiopulmonary bypass. Concomitant changes in oxygenation index and cardiac output were registered. Animals exposed to cardiopulmonary bypass showed a significantly higher technetium-99m-polymorphonuclear neutrophil accumulation in the lungs and kidneys, whereas indium-111-platelets accumulated in the heart and kidneys compared with the sham group. There was a significantly larger increase in oxygenation index and significantly larger decrease in cardiac output between the pre- and postcardiopulmonary bypass period in the cardiopulmonary bypass group compared with the sham group. CONCLUSIONS: The cardiopulmonary bypass procedure without cardiac surgery elicits organ dysfunction in terms of impaired respiratory and hemodynamic function. Platelets and polymorphonuclear neutrophils were entrapped in the heart, lungs, and kidneys of cardiopulmonary bypass animals, indicating that cell accumulation may contribute to the developing organ dysfunction.