Finally, the Spleen Gets Some Respect

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Finally, the Spleen Gets Some Respect

_http://www.nytimes.com/2009/08/04/science/04angier.html?_r=1 & em_

(http://www.nytimes.com/2009/08/04/science/04angier.html?_r=1 & em)

By _NATALIE ANGIER_

(http://topics.nytimes.com/top/reference/timestopics/people/a/natalie_angier/ind\

ex.html?inline=nyt-per)

 

As a confirmed crab apple who has often been compared to the splenetic

Lucy Van Pelt character from Peanuts, I am gratified to learn that should my

real spleen ever decide to vent in earnest, the outburst may just help save

my life.

 

 

Scientists have discovered that the spleen, long consigned to the B-list

of abdominal organs and known as much for its metaphoric as its

physiological value, plays a more important role in the body’s defense system

than

anyone suspected.

Reporting in the _current issue of the journal Science_

(http://www.sciencemag.org/cgi/content/abstract/sci;325/5940/612?maxtoshow= & HITS\

=10 & hits=10 & RESU

LTFORMAT= & author1=nahrendorf & andorexacttitle=or & andorexacttitleabs=or & fullte

xt=spleen & andorexactfulltext=or & searchid=1 & FIRSTINDEX=0 & sortspec=relevance & f

date=6/1/2009 & tdate=7/31/2009 & resourcetype=HWCIT,HWELTR) , researchers from

_Massachusetts General Hospital_

(http://topics.nytimes.com/top/reference/timestopics/organizations/m/massachuset\

ts_general_hospital/index.html?inline=n

yt-org) and Harvard Medical School describe studies showing that the

spleen is a reservoir for huge numbers of immune cells called monocytes, and

that in the event of a serious trauma to the body like a _heart attack_

(http://health.nytimes.com/health/guides/disease/heart-attack/overview.html?inli\

ne

=nyt-classifier) , gashing wound or microbial invasion, the spleen will

disgorge those monocyte multitudes into the bloodstream to tackle the crisis.

 

The parallel in military terms is a standing army,†said Matthias

Nahrendorf, an author of the report. “You don’t want to have to recruit an

entire

fighting force from the ground up every time you need it.â€

That researchers are only now discovering a major feature of a rather

large organ they have been studying for at least 2,000 years demonstrates yet

again that there is nothing so foreign as the place we call home.

“Often, if you come across something in the body that seems like a big

deal, you think, ‘Why didn’t anybody check this before?’ †Dr.

Nahrendorf

said. “But the more you learn, the more you realize that we’re just

scratching on the surface of life. We don’t know the whole story about

anything.â€

Dr. Nahrendorf, with Filip K. Swirski, Mikael J. Pittet and a dozen other

colleagues, performed the initial studies using mice, but the scientists

suspect the results will apply to humans as well.

Ulrich H. von Andrian, an immunologist at Harvard Medical School who was

not involved with the research, agreed that the findings were a surprise. “

If one had to guess the source of these cells, one would have thought it

likely that they were mobilized from the bone marrow rather than from the

spleen,†he said. “The discovery adds another layer of complexity not

previously associated with that organ.â€

The latest work also sounds a cautionary note against underestimating a

body part or dismissing it as vestigial, expendable or past its prime. In an

accompanying essay, Ting Jia and Eric G. Pamer of _Memorial Sloan-Kettering

Cancer Center_

(http://topics.nytimes.com/top/reference/timestopics/organizations/m/memorial_sl\

oankettering_cancer_center/index.html?inline=nyt-org)

admit that “the spleen lacks the gravitas of neighboring organs†like the

liver or the stomach “because we can survive without it.â€

Spleens can rupture during contact sports, say, or in a motorcycle

accident, at which point surgeons have no choice.

“It’s such a vascularized organ, and the risk of big-time hemorrhaging is

so great, that if the spleen ruptures, it’s a surgical emergency,†said

James N. George, a hematologist with the _University of Oklahoma_

(http://topics.nytimes.com/top/reference/timestopics/organizations/u/university_\

of_oklah

oma/index.html?inline=nyt-org) Health Sciences Center. “You have to

remove it.â€

The new findings in no way counter the necessity of excising a ruptured

spleen, the researchers said, but they do suggest that the loss of the organ

is more than a mere “inconvenience,†as it has often been depicted, and

could help explain previous reports showing an enhanced risk of early death

among people who have undergone splenectomies.

In one study that appeared in The Lancet in 1977, for example, researchers

compared a group of 740 American veterans of World War II who had had

their spleens removed as a result of battle injuries with a similar size sample

of veterans who had suffered other war injuries but had kept their

spleens. The splenectomized men, the researchers found, were twice as likely to

die of cardiovascular disease as were the veterans in the control group. All

of which means that despleening should be diligently guarded against,

particularly among our little sports warriors, perhaps through the wearing of

appropriate protective gear.

Researchers cite other cases in which organs were presumed to be so

dispensable that they could be removed “prophylactically†— often with

unfortunate outcomes. In recent years, for example, many older women undergoing

_hysterectomies_

(http://health.nytimes.com/health/guides/surgery/hysterectomy/overview.html?inli\

ne=nyt-classifier) have been advised to have their healthy

ovaries removed at the same time, the rationale being: if you are past

your childbearing years, why hang on to reproductive organs that might turn

cancerous and kill you? Yet follow-up surveys have shown that women who

underwent elective ovariectomy had a heightened risk of dying during a given

study period, were more susceptible to heart disease and lung _cancer_

(http://health.nytimes.com/health/guides/disease/cancer/overview.html?inline=nyt\

-clas

sifier) and were twice as likely to develop _Parkinson’s disease_

(http://health.nytimes.com/health/guides/disease/parkinsons-disease/overview.htm\

l?in

line=nyt-classifier) compared with women who had kept their ovaries. “

Evolution has an edge on us,†Dr. Nahrendorf said. “I would be very careful

about saying, ‘You don’t need this organ, get rid of it.’ â€

Another reason to esteem the spleen — a purplish, fist-size, five-ounce

organ in the upper left quadrant of the abdominal cavity, just behind the

stomach and under the diaphragm — is its illustrious medical and poetic

history. Galen considered the spleen to be a source of one of the four bodily

humors, specifically the black bile associated with irritable, melancholic

cranks. In his poem, “Spleen,†Charles Baudelaire describes a young narrator

so weary and despondent, unresponsive even to beautiful women and jesting

men, that it is as if the “green waters of Lethe†fills his veins.

More recently, researchers determined that the spleen is like an elaborate

wetlands, a Mississippi bayou for filtering and freshening the blood. In

other organs, blood flows through an interconnected mesh of increasingly

narrow arteries, veins and capillaries. The spleen, by contrast, has a

so-called noncapillary circulatory system: as the blood flows in, it is dumped

into

puddle-like sinusoids, and to get back out it must squeeze between cells.

That dumping and squeezing help filter out blood-borne parasites, aging

blood cells too brittle for compression and the little oxidized pellets, the BB

’s, with which red blood cells are often pocked. The spleen has often been

called a graveyard for red blood cells, but it is more of a recycling

center, for the iron and other components are plucked out of the cells and used

to stock new _hemoglobin_

(http://health.nytimes.com/health/guides/test/hemoglobin/overview.html?inline=ny\

t-classifier) cages.

Filtration, cannibalization, and now — serious monocyte cultivation. In

the new study, the researchers began by looking at monocytes, the largest of

the body’s white blood cells. “It was recognized that these cells are the

major repair workers after a heart attack,†Dr. Nahrendorf said. “They

remove dead muscle cells, they start rebuilding stable _scar_

(http://health.nytimes.com/health/guides/disease/keloids/overview.html?inline=ny\

t-classifier)

tissue, they stimulate the generation of new blood vessels.â€

The cells make haste to cut and paste. “Within 24 hours after a myocardial

infarction,†Dr. Nahrendorf said, “there are millions of monocytesâ€

congregating around the broken heart. All of which would seem sensible,

desirable, an excellent display of emergency preparedness, except that Dr.

Nahrendorf and his principal colleagues were puzzled by one big unknown: Where

did

the rapid response team come from? The numbers circulating in the blood were

simply too low. The researchers searched one organ after another, until

they checked the spleen and found the monocytic mother lode. “The numbers

there were huge, 10 times higher than what was in the bloodstream,†Dr.

Nahrendorf said.

By the researchers’ reckoning, monocytes, like all blood cells, are born

in the bone marrow and at some point migrate to the spleen, lured by cues

yet to be identified. They sit and wait, a sessile bunch, but when aroused by

such chemical signatures of damage as angiotensin, the cells surge forth

without hesitation, a reaction the researchers hope someday to understand

well enough to recapitulate at will. Hail to the chief, hail to the queen and

hail to the monocytes residing in my spleen.

 

 

 

 

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Intereting article - thank you for sharing.