LOS ANGELES (AP) _ Kay Lenz wanted to show the special problems faced by women with AIDS in her role on NBC's ''Midnight Caller,'' and so she talked with those who know best.

The actress, who won an Emmy for her portrayal of Tina Cassidy, met with a support group for women with AIDS in San Francisco. The episode, her third appearance as Jack Killian's former girlfriend, will be telecast Tuesday. Gary Cole stars as Killian.

''We decided to integrate the support group into the script,'' she said. ''They will go on Jack's radio show to inform the public about the specific problems of women. Everything these actresses say is true because we got it right from the mouths of the support group.

''The problem is that women don't have the political power that men have. They don't have the financial power. No matter how independent a woman is, it's part of a woman's nature to take care of others. Women with AIDS often have to take care of themselves. They're not prepared for this. Ninety percent of the women I met are mothers.''

Lenz added: ''Men with AIDS deal with friends and lovers. Women deal with family members because often their children may have it.''

Lenz won an Emmy last year as best guest actress in a drama series for her role on ''Midnight Caller.'' She first played the part in the series' pilot episode.

The AIDS episode last year caused considerable controversy in San Francisco, where the series is filmed. Lenz played a heterosexual woman who is infected by a man. In the first version of the script, the man is shot down in the streets. Protesters felt this would make AIDS victims into targets. The script was rewritten before it was filmed to eliminate the shooting.

In the current episode Tina is near death and Jack takes her in and comforts her.

''This is a very different show,'' said Lenz. ''We were taking a chance doing it again. We consulted many people, and the writer, Stephen Zito, did a lot of research. This show also talks about the isolation and prejudice attached to AIDS. It comes from ignorance, and from that comes abandonment and prejudice. If I so much as stub my toe I want a hug. It would be hard for me to imagine being that ill and being abandoned.

''It's the same kind of attitude people had about leprosy in biblical times. I hope we can reach the people who turn the channel whenever AIDS is mentioned ... I had a lot of ignorance about AIDS myself before I did this role.''

She said Jack and Tina have a wonderful relationship. ''They love each other unconditionally,'' she said. ''I love that it shows that people can have relationships. They may not work. She's lost her job as a teacher. Jack takes her in. It's a debilitating disease, but Jack's into denial. He doesn't want to accept that her life will never be the same again, nor will his.''

When she was first offered the role last year she talked to the producers about changing the character's name. Lenz was formerly married to actor David Cassidy. ''But they kept the name and it didn't bother me at all.''

Last summer, Lenz was seen as a police psychiatrist in the USA Network movie ''Murder By Night.''

She made her film debut in 1973 as a teen-age hippie in ''Breezy,'' which starred William Holden and was directed by Clint Eastwood. She was in the miniseries ''Rich Man, Poor Man'' in 1976 and the series ''Rich Man, Poor Man- Book II.''

Lenz has been a guest star on such shows as ''L.A. Law,'' ''Moonlighting,'' ''Hardball,'' ''Hill Street Blues'' and ''Cagney & Lacey.''

''I like doing series work,'' she said. ''I'm always a different character, although I'm usually a victim. I'm usually dying or a prostitute or pregnant. It allows you to have another life besides going to the studio.''

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