Sharon Berger, pictured, is battling her second bout of leukemia and needs a stem cell donor. Photo: AnthonyNolan.org.

Celebrities joined efforts to find a stem cell donor for a Jewish mother battling leukemia for the second time, The Jewish Chronicle reported on Thursday.

TV personality Sharon Osbourne, actor Matt Lucas and British boy band Blue are among the famous personalities that have shared online the hashtag “Spit4Mum” to help Sharon Berger, 65, from Kenton in northwest London. The campaign urges people to register to be stem cell donors through the UK-based charity Anthony Nolan, which helps those fighting blood cancer.

Osbourne tweeted, “A friend of mine has leukemia & needs a lifesaving stem cell donor – it could be you – please register & [re-tweet] RT,” while Lucas, who is Jewish, wrote: “Sharon Berger has leukemia & needs a lifesaving stem cell donor – it could be you – please register and RT.” London Mayor Sadiq Khan also re-tweeted a message backing the campaign.

Doctors said Berger has six weeks to find a donor for a transplant. Anthony Nolan is currently searching the world’s combined stem cell registries for someone whose tissue type matches Berger’s, according to Jewish News Online. Those interested in registering as donors must be between the ages of 16 and 30, in good health and weigh at least 110 pounds. Anthony Nolan said it is particularly looking for people “from Jewish and other ethnic minority backgrounds to join, as they are currently underrepresented on the donor register.”

Berger’s best match is likely to be an Ashkenazi Jew, because of her European heritage, but her family encourages all those eligible to join the bone marrow register.

Ann O’Leary, head of Register Development at the charity, said: ‘‘We’re extremely saddened to hear that Sharon’s cancer has returned and our thoughts are with her in her upcoming treatment. We will be doing all we can to support her and her family in the search for a donor.”

Three years ago, Berger was diagnosed with advanced leukemia and doctors said her only hope was a stem cell transplant. Her children started the #Spit4Mum campaign, which led to a 1,100 percent increase in the number of British Jews registering as donors, and eventually a match was found for Berger, The Jewish Chronicle reported. The transplant was successful, but two weeks ago, a routine blood test revealed the leukemia had returned.

Talking about the overwhelming support her mother is receiving, Berger’s daughter, Caroline, said: “We’ve been incredibly moved by the global support from celebrities on social media.”

“Now I hope we can turn those tweets into sign-ups to help save my mum’s life,” she added. “We are incredibly grateful that people in the public eye are putting the weight of their social media presence behind our #Spit4Mum campaign and using their celebrity status for the greater good.”

Caroline’s brother, Jonni, said, “We’ve had some amazing social media support which has taken our appeal to new audiences. It’s fantastic to see people getting behind our campaign so quickly. Retweets raise awareness but people have to take action, and that is the hard part.”