A Simple and Fast Single-Step Method to Isolate and Stain CD27 B Cells (Plasma Cells) Using Quantum Dot Magnetic Bead Antibody Conjugates for Fluorescent Microscopy

Objective: Conventional staining of mononuclear cells involves a two-step process: isolation followed by staining. This approach is time-consuming, and conventional dyes such as FITC, Cy3, or Cy5 exhibit photobleaching and broad emission spectra. This study aimed to develop a rapid, single-step method to simultaneously isolate and stain CD27-positive B cells using quantum dot magnetic bead antibody conjugates. Material and Methods: CD27-positive cells from immunized mononuclear cell cultures were incubated with quantum dot magnetic bead antibody conjugates (emission wavelengths 510 and 700 nm) and isolated using magnetic racks. Cells were then fixed on slides and observed under a fluorescent microscope. Results: In all 10 experiments, CD27-positive cells were successfully isolated and stained, emitting specific fluorescence corresponding to the conjugated quantum dots. Magnetic beads facilitated visualization under normal microscopy. The entire process was completed within 30 minutes. Conclusion: This is the first reported single-step method for isolating and staining CD27-positive B cells using quantum dot magnetic bead antibody conjugates, offering significant time savings compared with conventional two-step methods (>60 minutes). Quantum dot staining was stable over two years, demonstrating high photostability and bright fluorescence.