On Sunday, the actress' sister, Tracey Dowse, posted a message on the actress' Instagram account sharing the news and asking for prayers.
"As many of you have seen, my posts have been positive and up lifting [sic]. I am trying to keep my spirits up and support those who need it," she wrote. "As many of you know I am a private person. So this is hard for me."
"I am requesting support and prayers be offered me and my sister, and my only immediate family @denisedowse," she continued. "She is currently in the hospital in a coma brought on by a virulent form of meningitis. Her doctors do not know when she will come out of the coma as it was not medically induced."
Tracey concluded her note: "She is a vibrant actor and director that should have many years ahead of her. Thoughts, prayers and support are greatly appreciated."
Several stars such as actress Jill Marie Jones, singer Lalah Hathaway, and Dowse's 90210 costar Ian Ziering commented on the post, with the latter writing, "Sending prayers and hopes for better days ahead."
EW has reached out to Dowse's reps for comment.
Though she's perhaps best known for playing Mrs. Yvonne Teasley on Beverly Hills, 90210, she also played Judge Rebecca Damsen on CBS' The Guardian and Dr. Rhonda Pine on HBO's Insecure. Her long list of TV credits also includes stints on Grey's Anatomy, The Resident, Good Trouble, The X-Files, Criminal Minds, and many more.
On the film side, Dowse played Marlene in Ray, opposite Jamie Foxx, and Tyrone's mother in Darren Aronofsky's Requiem for a Dream. She's also known for roles in the '90s comedies Pleasantville and Bio-Dome.
Dowse is set to make her feature film directorial debut with the upcoming biopic Remember Me: The Mahalia Jackson Story, which follows the career of Jackson, her contribution to the Civil Rights Movement, and her friendship with Martin Luther King Jr. Keith David, Corbin Bleu, Vanessa Williams, and Columbus Short are set to star.