Background: Flow cytometry is a rapid, sensitive, and reliable method for determination of bacterial viability. Here we assayed the capability of flow cytometry to detect Helicobacter pylori viable cells in both forms of spiral and coccoid. Methods: Viable bacteria stained with Rhodamin 123 and fluoresced with laser beam of 488nm. The rate of Rh123 absorption was determined in both forms of bacteria. Results: In positive control that consisted of live bacteria, the rate of rh123 absorption was at highest, but negative control that consisted of dead bacteria, the rate of Rh 123 absorption was at lowest absorption. This method showed that non- culturable coccoid forms of H. pylori, which could resist environmental stresses, were alive and might be responsible for bacterial transmission and failure in disease treatment. Conclusion: Due to simplicity, reliability, and sensitivity of flow cytometry, this method is preferred to other expensive and no reliable methods such as autoradiography, PCR and Electron microscopy used for assessment viability.

Background: Chronic myelogenous leukemia (CML) is a myeloproliferative disorder due to BCR-ABL1 translocation. Patients showing transformation into blast crisis (BC) have poorer treatment response and prognosis. Methods: A retrospective study was conducted in the department of Pathology, Maulana Azad Medical College, New Delhi, India, over a time period of 5 years (2014-2019) to evaluate the immunophenotypic features of the blast population. Twenty-one Cases of CML in BC were subjected for multiparametric flow cytometry. Data of the subjects in CML blast crisis was compiled and analyzed for the immunophenotypic categorization of the blast population. Results: The mean age of the patients at presentation was 39. 84 years. Male to female ratio was 1: 1. 3. Out of 21 cases, 5 (23. 8%) showed blasts of myeloid lineage, 8 (38%) myelomonocytic, 6 (28. 5%) B lymphoid and 2 (9. 5%) showed mixed lineage blast population. Conclusion: Blast lineage in blast crisis of CML is heterogeneous and may show antigens of more than one lineage. Hence, it is necessary to evaluate the immunophenotypic nature of the blasts for the best appropriate management of the patients accordingly.

Flow cytometry, as a useful technology, has played an important role in the progress in basic and clinical research by measuring multiple char-acteristics of individual cells in a high-throughput manner. One of the most important applications of flow cytometry is the initial workup and subse-quent management of inborn errors of immunity (IEI). IEIs, also known as primary immunodefi-ciencies, are a heterogeneous group of inherited disorders of immune system, presenting with heterogeneous clinical manifestations. Given that IEI patients present heterogeneous clinical and immunological features, diagnosing IEI using only clinical and conventional laboratory data is challenging. Genetic tests, including whole exome sequencing (WES) and whole genome sequenc-ing (WGS), are involved in the identification of genetic defects in IEI; however, flow cytometry remains an important first step in defining the immunophenotype of the patient prior to genet-ic analysis. The applications of flow cytometry in the evaluation of IEI are diverse and include identifying distinct populations of immune cells, quantifying the expression of intracellular and intranuclear proteins, functionally validating ge-netic variants, monitoring treatment, defining the genotype-phenotype correlation, detecting carri-ers, and classifying disorders.