Terminal

WHEN SEAN returned from his meeting with Janet, he changed the direction of his investigations. Instead of attempting to characterize the antigenic specificity of Helen Cabot’s medicine, he decided to determine exactly how Louis Martin’s medicine differed from hers. A rapid electrophoresis of the two showed them to be of approximately the same molecular weight, which he’d expected. An equally rapid ELISA test with the anti-human immunoglobulin IgGl confirmed it was the same class of immunoglobulins as Helen’s. He’d also expected that.

But then he discovered the unexpected. He ran a fluorescence antibody test with Louis Martin’s medicine with Helen’s tumor and got just as strong a positive reaction as he’d gotten with Helen’s medicine! Even though Janet believed that the medicines came from the same source, Sean did not believe they could be the same. From what he knew about the antigenic specificity of cancers and their antibodies, it was extremely improbable. Yet now he was faced with the fact that Louis’s medicine reacted with Helen’s tumor. He almost wished he could get his hands on Louis’s biopsy just so he could run it against Helen’s medicine to confirm this baffling finding.

Sitting at the lab bench, Sean tried to think what to do next. He could subject Louis Martin’s medicine to the same battery of antigens he’d tried with Helen’s medicine, but that would probably be futile. Instead, he decided to characterize the antigenic binding areas of the two immunoglobulins. Then he could compare their amino acid sequences directly.

The first step of this procedure was to digest each of the immunoglobulins with an enzyme called papain to split off the fragments that were associated with antigen binding. After the splitting, Sean separated these segments, then “unfolded” the molecules. Finally, he introduced these compounds into an automated peptide analyzer that would do the complicated work of sequencing the amino acids. The machine was on the sixth floor.

Sean went to the sixth floor and primed the automated instruments. There were a few other researchers working that Saturday morning, but Sean was too engrossed in his work to start any conversations.

Once the analyzer was prepared and set to run, Sean returned to his lab. Since he had more of Helen’s medicine than he did of Louis’s, he used hers to continue trying to find something that would react with its antigen binding area. He tried to think what kind of surface antigen could be on her tumor cells and reasoned that it was probably some kind of glycoprotein that formed a cellular binding site.

That was when he thought of the Forbes glycoprotein that he had been trying to crystallize.

As he had been doing with numerous other antigen candidates, he tested the reactivity of the Forbes glycoprotein with Helen’s medicine using an immunofluorescence test. Just as he was scanning the plate for signs of reactivity, which he didn’t see, he was startled by a husky female voice.

“Exactly what are you doing?”

Sean turned to see Dr. Deborah Levy standing directly behind him. Her eyes sparkled with a fierce intensity.

Sean was taken completely by surprise. He’d not even taken the precaution of coming up with a convincing cover story for all his immunological testing. He hadn’t expected anyone to interrupt him on Saturday morning, particularly not Dr. Levy; he didn’t even think she was in town.

“I asked a simple question,” Dr. Levy said. “I expect an answer.”

Sean looked away from Dr. Levy, his eyes sweeping over the mess of reagents on the lab bench, the profusion of cell culture tubes, and the general disarray. He stammered, trying to think up some reasonable explanation. Nothing came to mind except the crystal work he was supposed to be doing. Unfortunately that had nothing to do with immunology.

“I’m trying to grow crystals,” Sean said.

“Where are they?” Dr. Levy asked evenly. Her tone indicated she would take some convincing.

Sean didn’t answer right away.

“I’m waiting for an answer,” Dr. Levy said.

“I don’t know exactly,” Sean said. He felt like a fool.

“I told you I run a tight ship here,” Dr. Levy said. “I have a feeling you didn’t take my word.”

“I did,” Sean hastened to say. “I mean, I do.”

“Roger Calvet said you haven’t been by to inject any more of your mice,” Dr. Levy said.

“Yes, well . . .” Sean began.

“And Mr. Harris said he caught you in our maximum containment area,” Dr. Levy interrupted. “Claire Barington said she told you specifically that area was closed.”

“I just thought . . .” Sean started to say.

“I let you know from the start that I did not approve of your coming here,” Dr. Levy said. “Your behavior thus far has only confirmed my reservations. I want to know what you are doing with all this equipment and expensive reagents. One doesn’t use immunologic materials to grow protein crystals.”

“I’m just fooling around,” Sean said lamely. The last thing he wanted to admit was that he was working on medulloblastoma, particularly after he’d been forbidden access.