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Tag: t-cells

04.15.2013

HIV testing by DVD

A recent paper in Lab on a Chip describes using a DVD player as a diagnostic tool. The researchers convert the optical drive into a laser scanning device that can count the number of CD4+ cells. From Phys Org:

Aman Russom, senior lecturer at the School of Biotechnology at KTH Royal Institute of Technology in Stockholm, says that his research team converted a commercial DVD drive into a laser scanning microscope that can analyse blood and perform cellular imaging with one-micrometre resolution. The breakthrough creates the possibility of an inexpensive and simple-to-use tool that could have far-reaching benefits in health care in the developing world.
“With an ordinary DVD player, we have created a cheap analytical tool for DNA, RNA, proteins and even entire cells,” says Russom. The so-called “Lab-on-DVD” technology makes it possible to complete an HIV test in just a few minutes, he says.
In a proof of concept demonstration, the researchers collected cell-type CD4 + from blood and visualized it using the DVD reader technology. Enumeration of these cells using flow cytometry is now standard in HIV testing, but the practice has been limited in developing countries.
HIV testing currently uses flow cytometry, which requires expensive equipment. If the DVD technique proves reliable, HIV testing can be done much more cheaply.

03.15.2013

CD4 cells are instrumental in controlling HIV infection

HIV medication

A report in Science discusses how a subset of CD4 cells could prevent HIV from destroying the immune system:

HIV preferentially invades T lymphocytes that have CD4 receptors on their surfaces. The resulting destruction of CD4 cells over a decade or so cripples the immune system and is the hallmark of AIDS. But the process takes many years because the central memory cell, a type of CD4+ T lymphocyte known in shorthand as Tcm, churns out clones of itself and can almost refill the body’s pool of CD4 cells as fast as HIV drains it. However, the downside is that some infected Tcm cells become reservoirs of latent virus that rekindle infection if antiretrovirals (ARVs) are stopped.

The report is based on a series of studies of HIV patients. In the first study 75 HIV patients were split into three different groups and received antiretroviral medications within 5 days of taking a blood test. When their blood was analyzed 24 weeks later, the level of HIV-infected Tcm cells was almost extremely low or undetectable. In another study researchers looked at why some patients were better able to protect their CD4+ cells without antiretroviral treatment:

The study compared nearly 300 infected people who had low levels of HIV in their blood, two-thirds of whom received treatment. The researchers found that elite controllers stood out in part because their Tcm cells downregulated a key receptor that HIV needs for entry and were less permissive to HIV infection. Conversely, Kitchen noted that people whose immune systems did not rebound even though ARVs controlled their infections had Tcm cells with impaired function.

Check the source link for more.

03.07.2013

salt linked to autoimmune disease

salt shaker

Salt has been linked to the production of TH17 cells by the immune system.

Yesterday, Nature published three research papers announcing that researchers have found a link to salt intake and autoimmune diseases like multiple sclerosis and lupus. In two of the papers, researchers were studying how TH17 cells in the immune system get switched on. These cells are a type of helper T cell that produces an inflammatory protein called interleukin-17 as part of the immune response. While looking for different triggers, the researchers discovered that TH17 activation was linked to the production of a protein called serum glucocorticoid kinase 1, or SGK1, that helps maintain salt levels in other cells. The researchers then saw that mice on a high salt diet had higher levels of SGK1 and more TH17 cells. From Scientific American:

The researchers found that mouse cells cultured in high-salt conditions had higher SGK1 expression and produced more TH17 cells than those grown in normal conditions.

“If you incrementally increase salt, you get generation after generation of these TH17 cells,” says study co-author Vijay Kuchroo, an immunologist at Brigham and Women’s Hospital in Boston, Massachusetts.

The research was then confirmed using a mouse model for multiple scelerosis and in vitro human cell culture. Again from Scientific American:

In the third study, researchers confirmed Kuchroo’s findings, in mouse and human cells. It was “an easy experiment — you just add salt”, says David Hafler, a neurologist at Yale University in New Haven, Connecticut, who led the research.

But could salt change the course of autoimmune disease? Both Kuchroo and Hafler found that in a mouse model of multiple sclerosis, a high-salt diet accelerated the disease’s progression.

All this evidence, Kuchroo says, “is building a very interesting hypothesis [that] salt may be one of the environmental triggers of autoimmunity”.

Whether this holds true in vivo for humans remains to be seen. It’s hard to generalize from in vitro cell culture as the immune system is highly regulated and that regulation can’t be simulated in a culture dish. And as I mentioned earlier this week, in many cases mouse models aren’t always good predictors for human systems.

//ptugnins.net/4/4535925