Ask A Scientist: Immunology Acronym Confusion

With so many acronyms used in the field of immunology, things can get confusing and mistakes can be costly. Acronyms are useful devices to reduce long, sometimes tongue-twisting terms into manageable shorthand, but do add confusion to those newer to the field.   

We’ve cleared up several of these situations through the years via our Ask A Scientist form, and we’re sharing some of the most common examples with you here.

What is the Difference Between PBMC and PBL?

PBMC is an acronym for peripheral blood mononuclear cells.

PBL is an acronym for peripheral blood lymphocytes (or leukocytes).

You will see PBMC used on our website because it more accurately describes our products. Our PBMC contain monocytes in addition to lymphocytes, so representing them as PBL would not be correct. Using the alternate “leukocyte” version of the PBL acronym would also be inaccurate since leukocytes include neutrophils, eosinophils, and basophils, which are not in our PBMC products.

Is it FBS or FCS?

FBS is an acronym for fetal bovine serum.

FCS is an acronym for fetal calf serum.

These terms are used interchangeably, and it’s really just semantics here. Both refer to the same thing.

FBS (or FCS if you prefer) is used for in vitro cell cultures because it contains a high level of growth factors.

You may have also heard of bovine calf serum (BCS) which is different from FBS/FCS and does not have the same level of growth factors.

We recommend FBS/FCS in some of our immune cell protocols.

Remember that bovine is to cattle as murine is to mouse — and there are many more examples where that came from. How many of these animal adjectives can you identify? (For fun, challenge a coworker!)

  1. Avian
  2. Caballine
  3. Cancrine
  4. Caprine
  5. Galline
  6. Lapine
  7. Lupine
  8. Ovine
  9. Porcine
  10. Simian

IT, IMT, IO?

Some people choose to abbreviate immunotherapy as IT, which can be easily confused with information technology — a field that deals with an entirely different set of viruses. Instead, use the accepted abbreviation IMT for immunotherapy to avoid confusion.

Some also falter over the use of immunotherapy and immuno-oncology. Immunotherapy involves stimulating the body’s natural immune system response to combat a disease. Immuno-oncology (IO or I-O) is a specific type of immunotherapy targeted to fight cancer.

When you’re referencing immunotherapy in relation to fighting cancer, choose the more descriptive and accurate immuno-oncology.

What is the Difference Between TLR and TCR?

TLR is an acronym for toll-like receptor.

TCR is an acronym for T cell receptor.

Toll-like receptors are proteins found on the membranes of sentinel cells like dendritic cells and macrophages. Their job is to recognize outside microbes that come in contact with the body and signal to B cells to initiate the innate immune response.

T cell receptors, although similar in acronym, are much different than toll-like receptors. TCRs live on the surface of T cells and are responsible for binding to antigen peptides. Upon recognizing and binding to the antigen, T cells are activated to become helper CD4+ or cytotoxic CD8+, both of which play a crucial role in the adaptive immune response.

What are TMB and TME?

TMB is an acronym for tumor mutation burden.

TME is an acronym for tumor microenvironment.

Not only do these acronyms look similar, but they sound similar as well. 

TMB is the measurement of the number of mutations in a tumor. Current studies are evaluating the use of TMB as a biomarker to determine if a patient is a good candidate for immunotherapies. It has been suggested that tumors with high TMB measurements may respond better to immune checkpoint inhibitors due to their neoantigens. (TMB in this sense is not to be confused with Tetramethylbenzidine, a chromogenic substrate used in staining.)

TME is a general term for the environment surrounding a tumor. The TME is typically comprised of blood vessels, various immune cells, fibroblasts, and the extracellular matrix. The tumor and its microenvironment have constant interactions and impacts on one another, with tumors secreting growth factors or influencing immune tolerance, and the TME playing a key role in the growth or restriction of cancer cells. Efforts are underway to manipulate the TME to favor anti-tumor immunity rather that suppress the immune response.

Are there other immunology acronyms you find confusing?

Comment below and we will add to our list.

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