Screening method

A method for screening cells secreting target antibodies, comprising the following steps:

• step (a):
• labeling a candidate cell with a first fluorescent molecule;
• step (b):
• adding the candidate cell labeled with the first fluorescent molecule and a labeled antibody against the target antibodies into a container fixed with a capture antigen to be mixed and incubated to obtain a cellular fluid;
• wherein the capture antigen is configured to specifically bind to the target antibodies;
• the labeled antibody is labeled with a second fluorescent molecule;
• the first fluorescent molecule has the following properties:
• a fluorescent light emitted after the first fluorescent molecule is excited by a first exciting light is different from a fluorescent light emitted after the second fluorescent molecule is excited by the first exciting light;
• the first fluorescent molecule is in a photo-activated state or a photo-converted state, the first fluorescent molecule emits a first fluorescent light after being excited by a third exciting light under the photo-activated state or the photo-converted state;
• the first fluorescent molecule emits a second fluorescent light after being directly excited by the third exciting light instead of a second exciting light;
• a wavelength of the first fluorescent light is different from a wavelength of the second fluorescent light, or a wavelength of the first fluorescent light is the same as a wavelength of the second fluorescent light but fluorescence intensities are different;
• wherein a wavelength of the first exciting light is different from a wavelength of the second exciting light;
• the wavelength of the second exciting light is different from a wavelength of the third exciting light;
• a wavelength of the fluorescent light emitted after the second fluorescent molecule is excited by the first exciting light is different from the wavelength of the second exciting light;
• step (c):
• observing the cellular fluid using a high content cell imager, exciting the second fluorescent molecule by using the first exciting light to emit the fluorescent light and screening the candidate cell surrounded by the fluorescent light, and labeling the candidate cell as a target candidate cell;
• then irradiating the target candidate cell with the second exciting light so that the first fluorescent molecule labeling the target candidate cell is in the photo-activated state or the photo-converted state;
• step (d):
• sorting the candidate cell in the cellular fluid using a flow cytometry, wherein in a process of sorting, the candidate cell processed in step (c) is irradiated using the third exciting light and the target candidate cell emitting the first fluorescent light is sorted, namely, the cells secreting the target antibodies.