Cell Line Authentication and Contamination: Why It Matters for Histology Too

We tend to file cell-line identity under "someone else's problem" — the culture lab's, not the histology lab's. That stops being true the moment a cell line is used to build an IHC control, a xenograft or an organoid model. A misidentified or contaminated line hands you a control you trust and shouldn't, and it does its damage quietly.

Two different failures

The first is misidentification — the line isn't what the label claims, usually through a mix-up or a faster-growing line quietly overtaking it. The tool that settles it is STR profiling against reference databases. The second is contamination, most often mycoplasma: invisible down the microscope, but perfectly capable of changing how cells behave and what they express.

Why it lands on histology's desk

If those lines feed a cell line microarray you're using as an IHC control, an unauthenticated line means your "known positive" might not express the marker at all — so a failed run can quietly pass. The same logic follows any xenograft or organoid model grown from the line.

What good practice looks like

STR-authenticate lines when they arrive and every so often after. Test routinely for mycoplasma, and quarantine anything new until it's cleared. Track passage number and source — very high passages drift. And keep the provenance documentation with any control block you make from a line. Controls exist to give confidence; authentication is what makes that confidence honest.