Question

Medical diagnosis of an immunodeficiency often involves the use of fluorescent antibodies specific for cell-surface proteins in order to distinguish particular cell types in a heterogeneous cell population moving in a stream. What is this technique is called?

a) flow cytometry
b) cell culture
c) cell fusion
d) fluorescence microscopy

Answer 1

The technique named in the question is flow cytometry, which is used to analyze and quantify specific cell types in a complex cell mixture via fluorescently labeled antibodies.

Step-by-step explanation:

The technique described in the question, where fluorescent antibodies specific for cell-surface proteins are used to distinguish particular cell types in a heterogeneous cell population moving in a stream, is called flow cytometry. Flow cytometry is an automated cell-counting system that detects fluorescing cells one at a time. It's particularly relevant in medical diagnoses of immunodeficiencies, such as HIV infections, to measure levels of CD4 T cells. The cells are stained with a fluorogen-conjugated monoclonal antibody (mAb) specific for cell markers like CD4, and then passed through a narrow capillary in the flow cytometer. A laser activates the fluorogen, allowing for cell quantification by a fluorescence detector positioned at an angle to the laser light.

Another application of flow cytometry is the fluorescence-activated cell sorter (FACS), which extends the capabilities of flow cytometry by physically sorting cells into subpopulations based on fluorescence intensity. Different charges are applied to the droplets containing the fluorescing cells, allowing for their sorting into different collecting vessels.