When Amit Gupta told his friends a few weeks ago that he had acute leukemia and needed a bone-marrow transplant, the word spread quickly.

Gupta, the 32-year-old founder of the do-it-yourself photography site Photojojo and the collaborative-working community Jelly, is not only beloved by his friends. (“One of the nicest, most genuine, most creative people you could ever meet,” is a typical encomium.) He’s something of an Internet sensation, with more than 14,000 Twitter followers. And he’s a former intern for Seth Godin, the best-selling author and marketing guru.

Gupta now has his own high-stakes marketing problem: how to persuade enough people to swab their cheeks and send in a genetic test kit to the national bone-marrow registry in hopes of finding a match for him.

Unlike blood or even kidney donations, the blood stem cells taken from marrow (“bone-marrow donation” is technically a misnomer) require an extremely close genetic match. Otherwise when some of the transplanted cells develop into white blood cells they will react to the rest of the patient’s body as if it were foreign tissue, triggering a serious, and potentially fatal, immune reaction. Gupta’s supporters say that because he is of South Asian descent, the odds of a match from the 9.5 million records on file at the U.S. registry is just 1 in 20,000.

When they heard his plight, Gupta’s tech-community friends immediately rallied to encourage more people to take the swab test. “We’re going to destroy those odds,” blogged his friend Tony Bacigalupo, who helped organize a New York swab party on Oct. 14. (India doesn’t have a registry, but people there can fill out a form at amitguptaneedsyou.com.) Twitter filled up with posts about how @superamit needed help.

Godin, however, wasn’t impressed. What he saw, he told me in an e-mail, was “a lot of digital handshaking” that amounted to “a feel-good waste.” Tweets alone wouldn’t get Gupta a transplant. Godin wanted to create a sense of urgency.

So he wrote a post on his own blog offering to pay $10,000 to anyone who became a match for Gupta and made the stem-cell donation, or to give the money to that person’s favorite charity. The offer, he says, was “a chance to say to my readers, ‘Hey, I care about this. A lot. Money where my mouth is.’”

He picked $10,000 because, he says, it’s “enough money to matter to both the giver and the recipient, without being enough money to sue over, cheat over or corrupt.”

Gupta’s friend Michael Galpert, one of the co-founders of the photo-editing site Aviary.com, quickly matched Godin’s offer. “I would do anything that could contribute to helping save his life,” he says.

With $20,000 at stake, the cause did indeed take on new urgency. Instead of just passing on news that Gupta needed help, people started bragging #IswabbedforAmit on Twitter. The money also made for a sexier news story. The website TechCrunch drove new waves of interest with an article headlined, “#IswabbedforAmit Offers Up 20K To Find A Bone Marrow Donor For Startup Founder Amit Gupta.”

There was only one problem. The offer was illegal.

Under the National Organ Transplant Act of 1984, better known as NOTA, it’s a federal crime to give or receive “valuable consideration” for any transplantable organ or tissue, specifically including bone marrow. (Expenses incurred in making a donation, including not only medical costs but also travel and lost wages, are exempt.)

The valuable consideration doesn’t have to be cash. A scholarship, a charitable contribution or even a free movie pass is enough to subject both parties to up to five years in prison and $50,000 in fines. Good intentions -- or fatal consequences - - be damned.

The law subscribes to what Viviana Zelizer, an economic sociologist at Princeton University, calls the “hostile worlds” view. This is the assumption that, as Zelizer puts it, “money and intimacy represent contradictory principles whose intersection generates conflict, confusion and corruption.”

As Gupta’s story illustrates, however, that’s not necessarily the case. Money can be an expression of commitment and a powerful spur to get people to act on their compassionate instincts. Financial incentives can overcome inertia and procrastination. They can steer people toward socially beneficial behavior. Nobel Prizes come with money, and we don’t, after all, expect every firefighter, nanny or transplant surgeon to work for free.

As someone with a long-standing interest in reducing the shortage of kidneys, I e-mailed the bad news to Godin as soon as I read his blog post. Although he calls the law “absurd on its face,” Godin revised his offer. He now promises the money to the first person who matches Gupta, regardless of whether that person goes through with the transplant: no quid pro quo.

Galpert, for his part, says he’d be willing to pay the fine to save his friend, but he, too, changed his offer to reward a match rather than a transplant. Nobody wants to face jail time. (On Monday a third friend, Jake Lodwick, added yet another $10,000 to the pot.)

“I’m confident that I’m within the letter of the law,” Godin says, “and have no desire to be a cause celebre.”

Fortunately, others are willing to take on that mantle. As a result, by the time Gupta finds a match, the law just might be overturned, at least as it applies to bone-marrow transplants.

In February, the 9th U.S. Circuit Court of Appeals heard arguments in a lawsuit challenging the constitutionality of the ban on valuable consideration for bone-marrow donations. The suit was brought by the Institute for Justice, a libertarian public-interest law firm, on behalf of plaintiffs who include patients, parents of sick children, a doctor who does bone-marrow transplants and a charity that would like to offer incentives, such as scholarships, to encourage more donations.

The lawsuit argues that since marrow cell transplants aren’t significantly different from blood transfusions, the federal government has no “rational basis” for outlawing the kind of compensation that is perfectly legal not only for blood but also for other regenerating tissues, such as hair and sperm, not to mention eggs, which don’t regenerate. This disparate treatment of essentially similar processes, it maintains, violates the Constitution’s guarantee of equal protection. A decision could come down any day.

Regardless of what you think of the ban on compensation for kidneys or other organs, argues Jeff Rowes, the lawyer handling the case, bone marrow is different. Not only do blood stem cells regenerate, but the most common donation process no longer involves anesthesia or a big scary needle to the hip bone.

About 70 percent of today’s bone-marrow donations use a process in which the donor receives injections of a drug that makes the body produce far more than the usual number of blood stem cells. The excess cells enter the bloodstream, where they can be extracted through the arm, just like normal blood donations, and then separated for transplant. The drug injections may cause aches in the days before the donation, but the process isn’t particularly painful or traumatic. It’s certainly easier than donating eggs.

Rowes also notes that the very difficulty of finding a bone-marrow match makes incentives all the more powerful. If a rich person could get thousands of people to register by offering a big reward to anyone who gives him a transplant, he would not only help himself but also anyone else who got cells from one of the people who registered in response.

Sure, some people would only give if they knew they were getting paid. But, once registered, many others would be happy to help someone else. Because a prize can overcome apathy and inertia, Rowes suggests, “there are huge positive externalities in the bone marrow context to allowing rich people to post big bounties.”

Amit Gupta is in a terrible situation, but he’s also lucky. He’s got lots of friends who not only want to help him but also have the connections and financial resources to change the odds of a match -- potentially saving not only him but other, less fortunate patients as well. Too bad the law only hinders such efforts.

(Virginia Postrel is a Bloomberg View columnist. She is the author of “The Future and Its Enemies” and “The Substance of Style,” and is writing a book on glamour. In 2006, she donated a kidney to a friend. The opinions expressed are her own.)

To contact the writer of this article: Virginia Postrel at vp@dynamist.com.

To contact the editor responsible for this article: Tobin Harshaw at tharshaw@bloomberg.net.