48 Advances in multiplexed ion beam imaging (MIBI) for immune profiling of the tumor microenvironment

BackgroundMultiplexed ion beam imaging (MIBI) combines time-of-flight secondary ion mass spectrometry (ToF-SIMS) with metal labeled antibodies to image 40+ proteins in a single scan at subcellular spatial resolution. Here, we show that the recently released MIBIscope provides improved sensitivity for detecting immune checkpoint markers and offers greater throughput at higher resolution than the alpha instrument.MethodsSerial sections from three FFPE NSCLC samples, in addition to a control slide consisting of various unremarkable tissues, were stained with a panel of 25 metal labeled antibodies. The tissue was imaged at subcellular resolution using the MIBIscope and the alpha instrument. Masses of detected species were assigned to target biomolecules given the unique label of each antibody and multi-step processing was used to create images. Cell classification was performed using two complementary methods that differed in the need for cell segmentation to phenotypically characterize the tissue environments and quantify marker expression.ResultsReplicate regions of interest (ROIs) were collected on both instruments with similarly sized ROIs acquired in 17 minutes with the MIBIscope compared to 280 minutes with the alpha instrument. Fourier Ring Correlation (FRC) showed the resolution to be greater on the MIBIscope as compared to the alpha instrument with FRC also demonstrating uniform resolution across an ROI 2.5X greater in size. Even with the 16X greater speed of the MIBIscope, the signal of the 25 markers across replicate ROIs was increased (y=x^1.07) and showed similar expression patterns to those observed on the alpha instrument (figure 1). This resulted in greater sensitivity to markers with low expression, such as checkpoint markers. Eleven cell populations were classified across the ROIs utilizing two methods, with both methods showing a similar frequency of tumor cells and B, T, and myeloid cell subsets between instruments. Segmentation enabled the number of cells within a population to be calculated but defining boundaries is laborious and signal from neighboring cells can result in misclassification. Performing classification at the pixel level, without segmentation, enabled the fraction of the tissue that is tumor or any other cell type to be rapidly determined.Abstract 48 Figure 1Comparison of images acquired between instrumentsThe signal intensity is greater on the MIBIscope and shows a similar staining pattern as achieved by the alpha instrument. Shown are 3 overlays from a single scan from replicate ROIs of an NSCLC sample displayed with the same contrast settings.ConclusionsThe MIBIscope enables the phenotypic characterization of tumor and non-tumor microenvironments. Co-expression of markers can be used to classify tumor and immune populations and to quantify the expression of markers associated with immune suppression. The increased sensitivity and throughput of the MIBIscope, in combination with the 40-parameter capability and subcellular resolution, provides a platform uniquely suited to understanding the complex tumor immune landscape.

Standard ultra-staging compared to one-step nucleic acid amplification for the detection of sentinel lymph node metastasis in endometrial cancer patients: a retrospective cohort comparison

IntroductionThe objective of this study was to compared standard ultra-staging (SU) with one-step nucleic acid amplification (OSNA) for the detection of sentinel lymph node (SLN) metastasis in women with apparent uterine-confined endometrial cancer.MethodsAll women underwent SLN identification with complete surgical staging. All SLNs were cut perpendicular to the long axis and two adjacent 5 µm sections were cut at each of two levels 50 µm apart. At each level, one slide was stained with hematoxylin and eosin and the other with immunohistochemistry using the AE1/AE3 anti-cytokeratin antibody, as well as one negative control slide for a total of five slides per block. For OSNA analysis, the 2 mm sections of the lymph nodes were homogenized to form a lysate. The lysate was then centrifuged and inserted into the RD 100i instrument where the isothermal amplification of CK19 mRNA was executed.ResultsOf the 396 patients included in the retrospective analysis, 214 were in the SU group, and 182 in the OSNA group. Overall 869 SLNs were identified (490 SU, 379 OSNA). Sixty patients exhibited SLN metastasis (34 SU, 26 OSNA). Macrometastasis, micrometastases, and isolated tumor cells (ITC) were 5.1%, 4.1%, and 0.2%, respectively, in the US group, and 2.4%, 6.3%, and 0.1%, respectively, in the OSNA group (p=0.022).ConclusionsThe OSNA assay detected a higher rate of micrometastasis and a lower rate of macrometastasis and ITC when compared with SU. The clinical and prognostic impact of ITC is debatable and controversial. Further studies are needed to clarify the respective roles of the OSNA and SU methods, and the possible role of ITC in the prognosis of patients with apparent early-stage endometrial cancer.

Educational technology and the traditional lecture

I was recently invited to give a lecture at the opening of a new high-technology lecture theatre at Leeds Metropolitan University. It is one of the best examples of its kind I have seen. Its impressive features include hi-fi surround sound, an enormous back-projected screen giving superb picture quality from either a VCR or directly from a computer for live demonstrations, online facilities, the latest remote-control slide-projection equipment, complete lecturer's control panel, and several nice touches such as automatic dimming of the auditorium lights when Play is pressed on any of the hidden video playback machines. The overhead projectors and their screens are of the best quality and correctly positioned for the clearest possible display. There are also video-link facilities for spill-over into a secondary lecture theatre which itself is well fitted out in presentational equipment.DOI:10.1080/0968776940020101

A Novel Quality Control Slide for Quantitative Immunohistochemistry Testing

We introduce a novel quality control technology that may improve intra- and interlaboratory immunohistochemistry (IHC) standardization. The technology involves the creation of standardized antibody targets that are attached to the same slides as the patient sample. After IHC staining, the targets turn the same color as the stained cells or tissue elements. Unlike current clinical practice, our proposed targets are neither cells nor tissue sections. To create reproducible standards that are available in unlimited supply, we use short constrained peptides as antibody targets. These peptides are attached directly to the glass slide. We show that these peptides simulate the portion of the native antigen to which the antibody binds. They are useful in detecting subtle changes in IHC staining efficacy. Moreover, the peptides do not degrade after deparaffinization or antigen retrieval treatments. This technology may be valuable in creating nationally standardized controls to quantify IHC analytical variability.

Pupillary Responses as a Measure of Attitudes about Alcoholic Beverages

Pupillary and verbal responses of 39 adult subjects were not significantly associated though mean pupillary responses while viewing slides of a seascape, an automobile accident, and a control slide were significantly different. There was a positive relation between stated dislike of the accident scene and pupillary constriction. Pupillary responses and Bell Alcohol Scale scores correlated —.42.

STAINING TOXOPLASMA GONDII WITH FLUORESCEIN-LABELLED ANTIBODY

A new serologic test for antibodies to Toxoplasma is described, which is based upon inhibition of specific staining with fluorescent antibody. In performing the test, a mixture of the test serum and known fluorescein-labelled antiserum is added to a dried smear of toxoplasms for 1 hour at 37°C. The smear is then rinsed and examined with a fluorescence microscope. Reduction in the brightness of fluorescence, as compared to that of a negative control slide, indicates the presence of antibody in the test serum. A comparison of the results of this test with those of the methylene blue dye test showed a strong parallelism between the two sets of results. On the other hand, the complement-fixation test for toxoplasmosis did not yield nearly as many positives as the inhibition test. The specificity of the new test was studied by comparing it with dye test results and clinical histories in human patients, and by testing a group of animals immunized with a variety of non-Toxoplasma antigens. No evidence of cross-reactions was obtained in the latter series. Some advantages and disadvantages of the inhibition test are discussed.