Flow cytometric detection of DNA tumor virus nuclear oncogene products in unfixed cells: saponin FACS of viral oncogene products

An image cytometric technique is a concise method to detect adenoviruses and host cell proteins and to monitor the infection and cellular responses induced

Background

Genetically modified adenoviruses (Ad) with preferential replications in tumor cells have been examined for a possible clinical applicability as an anti-cancer agent. A simple method to detect viral and cellular proteins is valuable to monitor the viral infections and to predict the Ad-mediated cytotoxicity.

Methods

We used type 5 Ad in which the expression of E1A gene was activated by 5′-regulatory sequences of genes that were augmented in the expression in human tumors. The Ad were further modified to have the fiber-knob region replaced with that derived from type 35 Ad. We infected human mesothelioma cells with the fiber-replaced Ad, and sequentially examined cytotoxic processes together with an expression level of the viral E1A, hexon, and cellular cleaved caspase-3 with image cytometric and Western blot analyses.

Results

The replication-competent Ad produced cytotoxicity on mesothelioma cells. The infected cells expressed E1A and hexon 24 h after the infection and then showed cleavage of caspase-3, all of which were detected with image cytometry and Western blot analysis. Image cytometry furthermore demonstrated that increased Ad doses did not enhance an expression level of E1A and hexon in an individual cell and that caspase-3-cleaved cells were found more frequently in hexon-positive cells than in E1A-positive cells. Image cytometry thus detected these molecular changes in a sensitive manner and at a single cell level. We also showed that an image cytometric technique detected expression changes of other host cell proteins, cyclin-E and phosphorylated histone H3 at a single cell level.

Conclusions

Image cytometry is a concise procedure to detect expression changes of Ad and host cell proteins at a single cell level, and is useful to analyze molecular events after the infection.

Electronic supplementary material

The online version of this article (10.1186/s12985-017-0888-0) contains supplementary material, which is available to authorized users.

Applications of flow cytometry to clinical microbiology

Classical microbiology techniques are relatively slow in comparison to other analytical techniques, in many cases due to the need to culture the microorganisms. Furthermore, classical approaches are difficult with unculturable microorganisms. More recently, the emergence of molecular biology techniques, particularly those on antibodies and nucleic acid probes combined with amplification techniques, has provided speediness and specificity to microbiological diagnosis. Flow cytometry (FCM) allows single- or multiple-microbe detection in clinical samples in an easy, reliable, and fast way. Microbes can be identified on the basis of their peculiar cytometric parameters or by means of certain fluorochromes that can be used either independently or bound to specific antibodies or oligonucleotides. FCM has permitted the development of quantitative procedures to assess antimicrobial susceptibility and drug cytotoxicity in a rapid, accurate, and highly reproducible way. Furthermore, this technique allows the monitoring of in vitro antimicrobial activity and of antimicrobial treatments ex vivo. The most outstanding contribution of FCM is the possibility of detecting the presence of heterogeneous populations with different responses to antimicrobial treatments. Despite these advantages, the application of FCM in clinical microbiology is not yet widespread, probably due to the lack of access to flow cytometers or the lack of knowledge about the potential of this technique. One of the goals of this review is to attempt to mitigate this latter circumstance. We are convinced that in the near future, the availability of commercial kits should increase the use of this technique in the clinical microbiology laboratory.

Applications of flow cytometry to clinical microbiology

Classical microbiology techniques are relatively slow in comparison to other analytical techniques, in many cases due to the need to culture the microorganisms. Furthermore, classical approaches are difficult with unculturable microorganisms. More recently, the emergence of molecular biology techniques, particularly those on antibodies and nucleic acid probes combined with amplification techniques, has provided speediness and specificity to microbiological diagnosis. Flow cytometry (FCM) allows single- or multiple-microbe detection in clinical samples in an easy, reliable, and fast way. Microbes can be identified on the basis of their peculiar cytometric parameters or by means of certain fluorochromes that can be used either independently or bound to specific antibodies or oligonucleotides. FCM has permitted the development of quantitative procedures to assess antimicrobial susceptibility and drug cytotoxicity in a rapid, accurate, and highly reproducible way. Furthermore, this technique allows the monitoring of in vitro antimicrobial activity and of antimicrobial treatments ex vivo. The most outstanding contribution of FCM is the possibility of detecting the presence of heterogeneous populations with different responses to antimicrobial treatments. Despite these advantages, the application of FCM in clinical microbiology is not yet widespread, probably due to the lack of access to flow cytometers or the lack of knowledge about the potential of this technique. One of the goals of this review is to attempt to mitigate this latter circumstance. We are convinced that in the near future, the availability of commercial kits should increase the use of this technique in the clinical microbiology laboratory.

Detection of p53 in inflammatory tissue and lymphocytes using immunohistology and flow cytometry: a critical comment

AIMS

To analyse the expression of p53 in lymphatic cells found in inflammatory tissues and the peripheral blood by immunological methods.

METHODS

Immunohistological analysis of synovial tissues from patients with rheumatoid arthritis and flow cytometric analysis of peripheral blood lymphocytes were performed with anti-p53 antibodies from different sources.

RESULTS

The anti-p53 antibodies PAb240, PAb421, and PAb1801 from one supplier bound to the cytoplasm of lymphocytes, fibroblasts, and endothelial cells in rheumatoid synovial tissue, while the same anti-p53 antibodies from other sources and the p53 specific antibodies PAb1620 and DO1 were negative. Using flow cytometry, the antibodies that labelled cells in inflammatory tissues were shown to bind also to peripheral lymphocytes, while the antibodies that were negative in immunohistology did not react with peripheral blood lymphocytes. p53 expression could be confirmed by western blot in rheumatoid synovial tissue, but not in peripheral blood lymphocytes using PAb421 and PAb240 antibodies from our own laboratory, which had been negative in immunohistology.

CONCLUSIONS

Demonstration of p53 by western blot is more sensitive and reliable than immunohistology and flow cytometry. Western blot is the gold standard for the demonstration of p53 expression and should be used, whenever possible, to confirm p53 expression in normal tissue shown by immunohistology or flow cytometry. All other reports on p53 expression, especially those obtained using antibodies with an unusual staining pattern must be interpreted with caution.