Population-averaged measurements combine signals from many cells, so a minority state can disappear within the overall profile. Single-cell proteomics retains the molecular signature of each analyzed cell, allowing researchers to compare cellular states rather than only a sample-wide average. This distinction is especially important when immune cells respond differently to activation or infection, revealing heterogeneity that bulk assays may conceal.
After lysis, digestion converts cellular proteins into peptides that can be measured and identified. Ultrasensitive mass spectrometry then links peptide signals to protein identities and quantities, while also enabling analysis of protein modifications. Together, these steps translate the limited material from one cell into molecular measurements suitable for comparing immune or infection-associated states.
Mass spectrometry measures identified and quantified peptides, including protein modifications, whereas antibody-based platforms provide complementary targeted measurements. A targeted antibody panel can focus analysis on selected proteins across individual cells. This distinction helps investigators match the platform to the research question, choosing targeted measurement when predefined immune-related markers are the priority.
A typical workflow starts by isolating or barcoding individual cells so their measurements remain attributable to the correct cell. Researchers lyse those cells, digest the released proteins into peptides, and analyze the peptides with ultrasensitive mass spectrometry. The resulting identifications and quantities are then compared across cells, enabling analysis of immune-cell states or infection-associated response patterns.
It is especially informative when cells within an immune sample may occupy different states during activation or infection. Cell-level measurements can distinguish heterogeneous immune responses, track signaling changes, and identify rare populations that population-averaged assays could obscure. Researchers can therefore examine host responses associated with infection and investigate how those responses vary among individual cells.
Profiles from individual cells can reveal molecular patterns associated with host responses and disease-related heterogeneity. Those patterns may support biomarker discovery and disease stratification by distinguishing groups with different cellular profiles. The same resolution can inform more precise therapeutic studies, where researchers need to evaluate responses at the level of individual cell states rather than relying only on a combined sample measurement.