In Vitro Differentiation of T Cells: From Nonhuman Primate-Induced Pluripotent Stem Cells

In this chapter, we describe a protocol for hematopoietic differentiation of nonhuman primate (NHP)-induced pluripotent stem cells (iPSCs) derived from T cells and generation of T cells. Derivation of T cells from PSCs involves three steps: induction of PSCs to hematopoietic progenitor cells (HPCs), differentiation of HPCs into progenitor T cells, and maturation of progenitor T cells into mature T cells, in particular CD8 single-positive (SP) T cells.

SFMAC: a novel method for analyzing multiple parameters on lymphocytes with a single fluorophore in cell-microarray system

The analysis of single cells with multiple parameters in flow cytometry or microscopy requires suitable combinations of fluorophores and optical filters. The growing demands for the multiplex analysis of cells increase the requirements for developing new fluorophores and techniques. We have developed a novel method of analyzing a large number of cells with multiple parameters on a single-cell basis using a single fluorophore. Cells were arrayed onto a microwell array chip with an array of 45,000 microwells, which could capture single cells, stained with a phycoerythrin (PE)-conjugated antibody to a marker, and analyzed with a cell-scanner. After analysis, we photobleached the PE molecules by irradiating the sample with blue light. Because the fluorescence of PE was not recovered after the photobleaching and the analyzed cells remained in the same microwells on the chip, we could repeatedly stain and analyze the same cells with other markers using PE. We applied a method of analyzing lymphocytes from 100 microL of peripheral blood for cytokine secretion and expression of intracellular proteins as well as for multiple cell surface markers. This novel method enables us to analyze multiple markers with a single fluorophore using a simple apparatus. The method may expand the scope of cytometry.

Evaluation of direct immunofluorescence test for diagnosis of upper respiratory tract infection by Chlamydia pneumoniae

BACKGROUND

Chlamydia pneumoniae causes a variety of respiratory infections and is involved in cardiovascular diseases. Diagnosis of C. pneumoniae infection currently relies on antibody detection by microimmunofluorescence (MIF), which has limited use, and is the retrospective diagnosis for acute infection.

OBJECTIVE

Find an effective early diagnosis of acute upper respiratory infection, or use in combination with MIF to accurately diagnose the infection by C. pneumoniae.

MATERIAL AND METHOD

Direct immunofluorescence (DIF) was developed to detect C. pneumoniae in nasopharyngeal specimens obtained from patients with upper respiratory tract infection, and normal individuals. IgM and IgG antibodies against C. pneumoniae by MIF were determined for evaluation of the detected C. pneumoniae and seroconversion.

RESULTS

DIF gave positive results in 29 of 37 (78.4%) samples from 31 patients. Fifteen samples positive by DIF illustrated antibody titers interpreted as acute C. pneumoniae infection, and eight DIF positive samples showed antibody titers of chronic infection. Negative results by both DIF and MIF were found in two patients and 23 of 25 by DIF but 20 of 25 by MIF in normal subjects. Five paired sera subsequently collected from three of the 31 patients illustrated seroconversion 2-4 months after the primary specimen collection, which gave positive results by DIF but negative for antibodies. Significant association was found between C. pneumoniae detection by DIF and antibodies by MIF when analysis was done in the group of patients and normal subjects (p < 0.001; Pearson chi-square test).

CONCLUSION

DIF could be an alternative assay for early diagnosis of C. pneumoniae infection, and may be used in combination with MIF for accurate diagnosis of acute C. pneumoniae infection.

A novel technique to eliminate cross-contamination when making wells on slides for rabies diagnosis

The direct fluorescent antibody (DFA) rabies diagnostic test requires demarcating desirable areas of brain tissue slip smear slides to be stained, traditionally achieved by applying paint from a tech pen or using a wax pencil to form a circle or dam-like ring or well into which rabies conjugate is expelled. Unfortunately, using these instruments poses a possibility of cross-contamination by transfer via the pen or pencil tip of rabies antigen from one slide to another. A new method was developed to avoid cross-contamination. The open end of a disposable glass test tube, dipped into a shallow reservoir of nail polish, was used to apply a dam-like ring about the slip smear area to be stained, after which the test tube was discarded, thereby precluding tissue transfer.

Report from a workshop on multianalyte microsphere assays

Multiplexed assays using fluorescent microspheres is an exciting technique that has been gaining popularity among researchers, particularly those in the public health field. Part of its popularity is due to its flexibility, as both immunoassays and oligonucleotide hybridization assays can be developed on this platform. This report summarizes a workshop held by the Centers for Disease Control and Prevention that discussed issues surrounding these assays and the Luminex 100 xMAP instrument. Topics included instrumentation, assay design, sample matrix and volume, quality control, and development of commercial applications.

Methods in virus diagnosis: immunofluorescence revisited

BACKGROUND

Immunofluorescence (IF) has been used in many laboratories for virus diagnosis but has begun to fall inappropriately out of favour as a diagnostic method as pressure on budgets and for objective quality control increases.

OBJECTIVES

To review the status, value and benefits of IF.

CONCLUSIONS

IF has, we believe, still a valuable role to play in routine virus diagnosis because it is rapid, accurate (with properly validated reagents), flexible and, by giving feedback on the quality of the specimens collected, promotes dialogue with the customer clinicians to their benefit and to that of the diagnostic laboratory. These benefits are not easily duplicated by other methods or techniques. While such rapid diagnosis primarily benefits the individual patient, providing results within a clinically relevant time has a secondary effect of increasing use of the service. It is our experience that the availability of rapid IF diagnosis (as opposed to culture or serology) for respiratory viral infections leads to a substantial increase in its use, thereby enhancing the amount and breadth of the resultant epidemiological data.

Immunofluorescence microchamber technique for characterizing isolated organelles

We describe a rapid technique for the localization and quantitation of specific proteins on organelles bound to microscope chambers. Disposable chambers are constructed from glass slides and provide a platform for the binding of organelles and subsequent immunofluorescence and biochemical assays. Several studies are presented to demonstrate the utility of this technique. Kinesin was visualized in postnuclear supernatants. Golgi and endoplasmic reticulum bound quantitatively to chambers. Endocytic vesicles prepared from rat liver that had been injected in situ with Texas red-labeled asialoorsomucoid allowed for simultaneous detection of asialoorosomucoid, asialoglycoprotein receptor, caveolin 1, and microtubules. Asialoglycoprotein receptor colocalized with asialoorosomucoid-containing vesicles, whereas many of the caveolin 1 structures had no asialoorosomucoid or asialoglycoprotein receptor. The microchambers were also used to measure the binding to endocytic vesicles of exogenously added Rab5 and to monitor the ATP-dependent acidification of endocytic vesicles using the fluorescent dye acridine orange.

Slide-format proteomic biochips based on surface-enhanced nanocluster-resonance

The most fundamental properties of metal nanoclusters, namely the high local-field enhancement and nanoscale resonance behavior of the cluster electron plasma when exited by electromagnetic radiation, have been used to set up a variety of sensors transducing biorecognitive interactions into optical signals. This paper focuses on applications of resonant-cluster technology, which enabled us to monitor biorecognitive binding of a variety of proteins on a chip, thus constructing high-throughput interaction-screening devices. Decisive for this type of sensor is the nanometric distance from the local field surrounding a cluster to other parts of the sensor interacting with this field. In particular, the cluster-mirror or cluster-fluorophore distance gives rise to a variety of enhancement phenomena. Depending on the desired application this "resonance"- distance is approximately 5-400 nm. All types of sensor can be set up on photolithographically constructed microchips, but microscopic glass slides can also be employed; this also enables the use of standard devices for dotting and read out. Using slide based chips a standard format of 3,200 microdots (125 microm in diameter) was the basis of either microassays applying direct optical transduction via surfaceenhanced absorption or striking for more sensitivity via surface-enhanced fluorescence.

An automated fluorescence based assay of neurite formation

The assessment of neurite-promoting activity of growth factors and neurotrophins in vitro is usually done by the laborious process of counting neuronal processes manually under a standard microscope. This often requires fixation of the cells so that samples can be counted over a period of days when large numbers of cells or samples are assessed. This, therefore, limits the investigator to a single time point for that plate of cells. In an effort to provide an assay that could be used to screen samples quickly to grade overall neurotrophic activity, and to study time-dependent responses easily, an assay is described that quantitates neurite formation based on automated fluorescence detection. Dissociated embryonic mouse dorsal root ganglion neurons were placed in the upper chamber of 1 microm pore size Fluoroblok (Falcon) transwell chambers. The porous membrane of these transwells is optically opaque. NGF placed in the lower chamber of the transwell induced the production of neurites that preferentially passed from the neuronal cell body in the upper chamber through the pores into the lower NGF-containing chamber. The degree of neurite production was assessed both in live cells and in fixed cells by fluorescent labeling of the neurons and neuronal processes. Quantitation of neurite formation was done with a multiwell fluorescence plate reader and verified by confocal microscopy. This method allows the screening and quantitation of neurotrophic activity in both primary neurons and neuronal cell lines. In addition, this also provides experimental access to neuronal processes that are optically separated from the cell body. The latter aspect may also be of great use where fluorescence measurements within neurites and growth cones, such as for Ca2+ release studies, need to be isolated from contaminating fluorescence or synaptic influences of cell bodies.