Lyt-2-/Lyt 3- variants of a cloned cytolytic T cell line lack an antigen receptor functional in cytolysis.

To investigate the role of Lyt-2 and Thy-1 in cytolysis, we have generated, by ethyl methanesulfonate mutagenesis and selection, variants of the cloned cytolytic T lymphocyte line L3 that specifically lack either Lyt-2 or Thy-1. An analysis of these variants indicates that neither Lyt-2 nor Lyt-3 is responsible for the lethal hit, but suggests that Lyt-2 and/or Lyt-3 are required for an antigen receptor functional in cytolysis. The data also suggest that the expression of Lyt-3 on the cell surface is not independent of the expression of Lyt-2.

Structural differences in cell surface T25 polypeptides from thymocytes and cloned T cells.

The molecule bearing the Thy-1.2 antigen, T25, has been isolated from fractionated thymocytes as well as from cloned cytolytic and helper T cells by immune precipitation with monoclonal antibodies. Using NaDodSO4/polyacrylamide gels cross-linked with N,N'-diallytartardiamide, electrophoretic analyses of the precipitates revealed a heterogeneous pattern of polypeptide bands, ranging in apparent molecular weight from 28,000-36,000 daltons.

Evaluating optical filter efficiency in a flow cytometer.

A simple yet effective method of testing optical filters under normal operating conditions on a Fluorescence Activated Cell Sorter is described. The spectral characteristics of three filters are compared to demonstrate the methods of determining which filter is the best in a particular situation. These tests include determining the efficiency of transmitting fluorescent light, determining the efficiency of removing scattered light, and detecting fluorescence originating from the filter itself.

Simultaneous quantitation of Hoechst 33342 and immunofluorescence on viable cells using a fluorescence activated cell sorter.

The cytochemical stain Hoechst 33342 has been used to quantify DNA in viable cells and has been used under nonsaturating conditions to discriminate between lymphoid cell types. In order to correlate the quantitative emission from Hoechst 33342 with cell surface antigens, a fluorescence activated cell sorter was modified to simultaneously detect emission from the UV excited Hoechst dye and fluorescein attached to the cell surface by immunofluorescence techniques. A special set of laser mirrors was installed in an argon ion laser so that all the lines from 351-488 nm could be used to illuminate the cells.

The scintigraphic appearance of the spleen following splenic artery resection.

Sequential 99mTc-sulfur colloid scans were performed on 4 patients following resection of the splenic artery and vein during donor pancreatectomy. Immediate postoperative scans showed markedly decreased or absent uptake. Over a period of two weeks the appearance returned to normal in 3 and peripheral defects were seen in 1.

Interaction between I region loci influences the expression of a cell surface Ia antigen.

Loci clustered in the I region of the murine H-2 gene complex control the capacity to generate an immune response against foreign antigens (Ir loci) and control differentiation antigens which appear to serve as structures used by cells to interact with and regulate one another (Ia loci). Both genetic and functional studies suggest that Ia antigens may be products of Ir loci. Recent studies have shown that interaction between closely linked Ir loci is required for generating immune responses to certain foreign antigens, and that interaction between H-2-linked loci determines the appearance of an Ia glycoprotein (the Ae chain) on lymphocyte cell surfaces.

A perspective on the usefulness of computers in nuclear medicine.

A computer system in clinical nuclear medicine has a wide variety of operations which it can perform. These range from simple data acquisition and tabulation to elaborate temporal and spatial reconstructions. Simultaneous recording of physiological data has also expanded the number of nuclear medical studies possible.

Localization of radiolabeled mouse alloantibody in a sarcoma induced by 3-methylcholanthrene.

The distribution of twice-purified I-125-labeled alloantibody, prepared from the serum of strain DBA/2J mice obtained after immunization with strain C3H/HeJ spleen cells, was studied in immunosuppressed DBA/2J mice bearing either an allogeneic C3H/HeJ MCA sarcoma (i.e., one induced by 3-methylcholanthrene) or a syngeneic MCA sarcoma.

Separation of viable T and B lymphocytes using a cytochemical stain, Hoechst 33342.

Data are presented that show that a histochemical stain, Hoeschst 33342, can be used to discriminate between viable B and T lymphocytes in the mouse. Quantitative analysis of the staining of cells from various lymphoid tissues with Hoechst 33342 using a Fluorescence-Activated Cell Sorter (FACS) indicates that two populations of cells can be identified. In the spleen approximately 60% of the lymphocytes can be classified as brightly stained with 1 microgram/ml of Hoechst 33342, while in the lymph node only 40% of the cells stain brightly.

Ovarian imaging by the binding of radioiodinated chorionic gonadotropin: concise communication.

Previous studies have demonstrated the presence of specific, high-affinity receptors for human chorionic gonadotropin (HCG) in human and rat ovaries. In the present study, highly purified HCG was labeled with iodine-131 and used for the imaging of luteinized rat ovaries. Excellent images were obtained.

False-positive 111In-labeled leukocyte scan in cystic fibrosis.

A false-positive 111In-labeled leukocyte scan was obtained in a girl with cystic fibrosis and infection. There was focal accumulation of 111In activity in the abdomen and marked pulmonary uptake. Surgical exploration and postmortem examination revealed no abdominal abnormality.

Clonal evolution of myeloma cells leads to quantitative changes in immunoglobulin secretion and surface antigen expression.

We report that a cloned population of tumor cells can rapidly produce variants that differ in their quantitative expression of surface proteins and in their rate of immunoglobulin secretion. A fresh clonal isolate of S107 myeloma cells possessing large amounts of surface IgA was continuously passaged in vitro for 2 years. During this period, fluorescence-activated cell sorter analysis indicated the development of subpopulations possessing decreased amounts of surface IgA.

Evaluation of three imaging instruments in dogs with liver hemotomas: concise communication.

Single-gamma emission computerized tomography (ECT) was compared with transmission computerized tomography (TCT) and scintillation-camera imaging (SC) in eight dogs with acute, solitary hematomas in the left liver lobe. The superior performance of TCT was attributed to its inherently better spatial resolution than those of ECT or SC, and to the fact that studies with TCT could be performed during apnea. ECT was more sensitive than SC to small changes in the spatial distribution of radionuclides.