clinical trial qualification
October 15, 2005 1:40 AM   Subscribe

I might be rejected from a clinical trial because of low CD3/4 levels. Help me understand what this means.

"Your results were 490 cells/uL and the normal range is 496-1354," I was told via e-mail without any further explanation or information, and I've been fruitlessly googling since. The trial has to do with severe psoriasis.
posted by goofyfoot to Health & Fitness (8 answers total)
"CD" (cluster of differentiation) proteins are proteins present on the surface of cells that are used as markers to identify particular cell types. CD3 and CD4 are just two of the hundreds of CD proteins there are. Both CD3 and CD4 are present on T cells, which are a type of white blood cell and are a component of the immune system. I know that T cells are supposed to be somehow involved in psoriasis, probably by being involved in the autoimmune reaction that causes the lesions of the condition, but I don't know more than that.

The trial might involve somehow inhibiting T cells as a treatment for the disease, and they don't want to complicate matters by studying someone who's already got relatively low T cell counts.

Here's a table of some of the CD proteins if you're interested.
posted by shoos at 3:02 AM on October 15, 2005

You shouldn't have to ask strangers. You have consented to participate in this trial, or have at least consented to be screened for eligibility, so the investigator or physician responsible for the clinical trial owes you an explanation (maybe not legally, but morally they owe you), especially if your situation signals a more serious problem. If they won't give you an explanation that satisfies your curiosity or need to know, then go to the IRB or research ethics board responsible for this study and ask them for help.

Where is the clinical trial?
posted by mds35 at 5:42 AM on October 15, 2005

Response by poster: Los Angeles is where I was recruited, by what I gather (have been googling) is a sort of an office hub for screening processes . That's not unusual or unethical. I got worried when I was told, without further information, this bit of information I posted above.
posted by goofyfoot at 7:06 AM on October 15, 2005

If none of the MeFi doctors (or biochemists) take this one, you should ask your personal doctor.
posted by abcde at 9:55 AM on October 15, 2005

Goofy, it's unusual AND unethical for the recruiters for the study to say that you might have a medical condition and not give you any explanation of it. The physician in charge of the recruiting, or the nurse that checked you out and sent you that email, ethically owes you an explanation. In any medical study, if you've been screened for it, you should know what study it is, who the sponsor of the study is, and have a way to contact the sponsoring organization and their oversight board.

If none of the above are true ... you should report the business that screened you to the state medical board. Seriously.
posted by SpecialK at 10:40 AM on October 15, 2005

OK. Let's talk about white blood cells for a moment.

In your blood are red blood cells and white blood cells. Red blood cells carry oxygen around. White blood cells are part of your immune system.

White blood cells are further subdivided into lymphocytes, granulocytes, macrophages, eosinophils, and basophils.

Lymphocytes are further subdivided into T cells (CD3 positive cells), and B cells (CD3 negative cells.)

T cells are further subdivided into CD8+ T cells (cell-mediated immunity) and CD4+ cells (helper T cells).

There are further subdivisions - each of these cells is marked for its special job in the immune system, it's like a highly choreographed dance - but you probably don't care.

For some reason, your CD4 count is slightly out of the normal range, which is a 95-percentile range of healthy people. That means that, when that blood was drawn, either you were in the 4th percentile of healthy people; or you were not healthy.

Lots of immune problems, including psoriasis, can muck up your T-cell levels. However, and this is the elephant in the room that I feel like everyone is waiting for someone else to bring up: HIV infection can also lower your CD4 count. In fact, when unethical doctors want to test people for HIV without informing the patient that they're doing so, they get a CD4 count. Obviously you wouldn't want to recruit someone into your immuno-suppressive trial if they had HIV; extra immunosuppression kills HIV+ people quick.

Does this mean go to your doctor and get an HIV test? Well, that's kind of up to you.
posted by ikkyu2 at 11:05 AM on October 15, 2005

Er. Actually, you'd be in the 2nd percentile, not the 4th.

Also, I second the comments of the above posters. When your blood was taken you should have obtained an informed consent form and that form should have had a phone number to contact someone at the study on it with your questions. Call that number and demand a clear explanation, it is your right to do so. As someone who has conducted clinical trials, I want you to know that:

- We care about the people who agreed to try to help us in the name of science.

- We are available to you for questions that come up as a result of our actions, by law and by generally accepted ethical guidelines.

- We know that our ability to conduct trials in an ethical fashion relies in part on your participation in this process; we can't read your mind, we can't know that our email worried you unless you tell us so.

So dig out that number and call 'em up.
posted by ikkyu2 at 11:11 AM on October 15, 2005

Response by poster: I can't get ahold of these people over the weekend, which is why I posted this question.

Thanks for the response! I have no health insurance, therefore no doctor to query (and am HIV-, so the faqs I've found re CD3 and CD4 haven't been much use).
posted by goofyfoot at 12:18 AM on October 16, 2005

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