SIX-YEAR-OLD MEETS GERMAN DONOR MAN CREDITED WITH SAVING BOY'S LIFE.

Byline: Paul O'Donoghue Staff Writer

THOUSAND OAKS - Emotion overwhelms Shannon Koss every time she thinks of the man from Germany who donated bone marrow so her only son could live.

The man, Fritz Hopster, and his family arrived from Europe at Los Angeles International Airport on Saturday to stay with the boy, Steven Koss, 6, and his family at their home in Thousand Oaks.

And that's when both families met face-to-face for the first time, following Steven's bone marrow transplant in December 1997 that required both parties to remain anonymous until more than a year afterward.

``I saw Fritz, and I hugged him and I cried,'' said Koss, grasping Hopster's arm, tears filling her eyes.

``I still cry when I see him and look at his eyes. This is the wonderful man who saved my son's life.''

And Shannon and her husband, Steve, hosted a party at their home on Sunday attended by about 40 family members, friends and neighbors to thank Hopster for donating the life-giving marrow needed by Steven against aplastic anemia.

The potentially deadly disease prevents the body from producing oxygen-carrying red blood cells, disease-fighting white cells and blood-clotting platelets.

Hopster, 43, an engineer, is accompanied by his wife, Magdalena, 48; three children, Marcel, 23, Ilka, 19, and Tobias, 17; and his wife's nephew Henrik Borghorst, 25. For the Hopsters, meeting with Steven and his family, and coming to the United States for the first time was the fulfillment of several dreams.

``I feel like Steven is my fourth child because I have saved his life,'' said Hopster in halting English.

``That makes me very proud,'' he said.

At the party, Steven, looking like any other healthy 6-year-old, raced around, playing with gifts he'd received, making like a young Jimi Hendrix on a guitar-shaped music player that blasted rock tunes, and flying around on a tricycle as adults played hoops.

Turkey, potatoes and vegetables were being cooked - some of Steven's favorite food.

``I think it's all very exciting,'' said Steven, shyly sizing up the party. ``It's going to be so fun, I think.''

It was a far cry from 1996, when he was first diagnosed with the rare disease that weakens the immune system, makes victims prone to infection, weak and tired, and often leads death.

Because of fear of infection, Steven could not play with other children.

And a string of disappointments dogged the Kosses as they sought to save their son, who required regular blood transfusions.

They waited for a match from any one of the 4 million people on the National Marrow Donor program registry. Meanwhile, Steven went through months of chemotherapy and radiation treatment and spent months in the hospital.

The Kosses' daughter, Serena, was born in 1996, and at first her bone marrow appeared to be a perfect match for Steven's, but that turned out not to be the case. And two other people whose marrow matched dropped out of the national program.

But Fritz's marrow matched. Like nearly everyone in his home town of Haren, population 15,000, he went on the bone marrow national registry about five years ago when a young local girl needed a transplant.

While his marrow didn't match the girl's, he was a perfect match for Steven's needs. And when he was asked to donate bone marrow for a child in America, he didn't hesitate.

The Hopsters are staying with the Kosses, who plan on showing them around some of the places the German family has dreamed for years of visiting, including Las Vegas, Malibu, Disneyland and Hollywood.

Speaking for the family, Ilka Hopster said meeting Steven and his family has been too exciting to feel jet-lagged after a 12-hour trip from Europe.

``I think we're too excited to be tired,'' she said. ``It's so interesting and so nice, there's no time to be tired.''

And for the Kosses, words aren't enough to express how they feel as Steven, who still needs regular checkups and is home-schooled by Shannon, gets closer to the five years after the operation that is a milestone in determining whether the transplant worked.

``We take it one day at a time and thank God for every day we have with him, and for Fritz,'' Shannon said.

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2 photos

Photo:

(1 -- ran in Valley and Conejo only -- color in Conejo only) Six-year-old Steven Koss wraps his arms around Fritz Hopster of Germany on Sunday.

(2 -- ran in Conejo and Simi only) Shannon Koss, left, Fritz Hopster, bone-marrow recipient Steven Koss, Scott Koss, Magdalena Hopster and Serena Koss gather Sunday in Thousand Oaks.

Gus Ruelas/Staff Photographer