What is that smell when you have the flu or a cold?

[spluurtaf]

Every time I get a cold or flu, I always get this weird smell when I breathe in through my nose. Does this happen to anyone else, and what causes this?

[minty green]

You mean that metallic kinda smell? Dunno, but I'd love to hear from somebody who does.

[justwannano]

I'm interested too.
I thought that metalic smell had to do with sinus infection.

[Alias]

I'm thinking it's the smell of mucous... Does someone have a better hypothosis?

[minty green]

Who the heck can actually smell anything with a head full of snot? It always struck me as more of a sensation of smell than anything I was really smelling. If that distinction makes any sense...

[jb_farley]

I think it's the smell of diseased, pussy snot. Lots of dead leukocytes and stuff.


jb

[choosybeggar]

nitpick: Colds and influenza are viral infections. Pus formation (main component-dead neutrophils) occurs in bacterial infections.

I'm not sure whether there's a huge cellular influx into the inflamed nasal mucosa. If there were inflammatory cells there, though, they'd more likely be lymphocytes and monocytes.

As to the OP: I've noticed a distinct odor as well. I attribute it to either:

1) a non-cellular component that is extravasated or produced locally in response to inflammation and can tickle the olfactory receptors

2) changes in the environment of the olfactory receptors secondary to inflammation (eg. different ionic consistency or pH of inflamed tissue) that induce "false signals" from the olfactory receptors. These are interpreted by the brain as a smell

[jb_farley]

what becomes of the lysed cells in a viral infection? do they get turned into something like pus, or not at all?

could you be, by some chance, actually smelling the viral particles?


jb

[choosybeggar]

Originally posted by jb_farley
what becomes of the lysed cells in a viral infection? do they get turned into something like pus, or not at all?

Probably not at all. The most important cells in combatting a viral infection are lymphocytes, T cells and B cells. A subset of T cells (CD8 T cells) directly and specifically kill virus infected cells. During a viral infection, the virus-specific CD8 T cells undergo a dramatic expansion (in experimental viral infections in the mouse they can come to represent 20% of the total pool of CD8 T cells, while prior to infection, they are difficult if not impossible to detect). They can concentrate in the infected tissue but are also found at body sites remote from the infection. With resolution of the infection, the number of virus-specific CD8 T cells diminishes rapidly. But they don't form pus. Instead, they die by a process termed programmed cells death (apoptosis). Basically this is cellular suicide. It happens when a cell realizes it is no longer of any use to the host (Such nobility!. Cells that die by programmed cells death are rapidly gobbled up by macrophages, the immune system's sanitation department.

B cells are the antibody producing cells and they can be very important in viral immunity as well. In fact, the way that the influenza vaccine (and many other antiviral vaccines) works is by inducing an antibody response that protects the host from infection from a given influenza strain. Antiviral B cells also expand during an infection or with immunization, but to a much lesser degree than CD8 T cells. In a vigorous response, the anti-viral specific B cells population is probably at most around 0.5% of the total B cells in the host. With resolution of the infection, the majority of these die (by programmed cell death) and are gobbled up by macrophages. An important subset of the original antiviral B cells persists to become memory B cells/plasma cells. These can continue to secrete anti-viral antibody for a long time (years) giving the host long-lasting immunity.

Originally posted by jb_farley
could you be, by some chance, actually smelling the viral particles?jb

Usually odorants are small volatile molecules. That way they can swim through the air into your nose. Smell receptors probably target molecules with such characteristics. Viral particles are large (relative to the typical odorant) and composed of protein and carbohydrate. While I wouldn't rule out a chance interaction with an olfactory receptor, I think the likelihood would be low.

[jb_farley]

sweet! thanks choosybeggar.

Remember, beggars can't be choosy, but choosy beggars choose Jif.


jb