FINDING THE ANSWER TO MS IS LIKE:
- Solving the mystery
- MS is an autoimmune disease which damages myelin and starts a chronic degenerative process in the brain and spinal cord.
- Systemic autoimmune diseases like Lupus affect the whole body. They reflect a widespread derangement in immune function.
- Restricted autoimmune diseases like MS are confined to one tissue or organ. This type of disease is primarily due to a defect in function of certain immune cells known as T regulatory cells.
- The failure of T regulatory cells is the result of a long developmental process which precedes the onset of clinical MS; and which involves genetic inheritance as well as environmental influences acting on these cells to ultimately disturb their normal function.
- T regulatory cells normally act to suppress the function of other immune cells called T effector cells, which prevents the development of autoimmunity. In the case of autoimmunity such as MS, the T regulatory cells may not only fail to function but may change to function like T effector cells which cause inflammation and tissue (myelin) damage.
- The key to understanding this process in MS is to define the stages of function and malfunction of T regulatory cells and the resultant dysfunction of unrestrained T effector cells. This is the goal of the research we do at MSRI.
- Flow cytometers and Cell sorters are invaluable pieces of laboratory equipment which allow us to dissect the processes in immune cells which lead to the development of MS. Understanding these processes will also allow us to rationally design more specific treatments for MS.
WHAT IS FLOW CYTOMETRY?
Flow cytometry is a technique used to study the surface and interior of immune or other cells. It has many innovative uses but we mainly use it at MSRI as a cell biology tool to study immune cells. This technique is integral to and has revolutionized much of contemporary immunology.
First, cells are prepared for the analysis. Antibodies against defined molecules on the surface of the interior of the cells are reacted with the cells. Each specific antibody is labelled with a small molecule called a fluorochrome – and different antibodies are labelled with different fluorochromes to distinguish between them. A suspension of the cells is then passed in single file through a flow cell where it interacts with a laser beam. When the cell is exposed to a particular and narrow wavelength of light from a laser the relevant fluorochrome fluoresces at a defined wavelength and this fluorescence and its intensity are then read by the flow cytometer. Different lasers excite different fluorochromes, so that more than 20 molecules can potentially be studied simultaneously in different cell populations.
So, for example we can distinguish between a cell with a surface that expresses A B C and D, etc., and differentiate it from a cell that expresses A B F and G. Because we can also look at molecules inside a cell as well we can determine whether these cells are similar or different in internal molecules which may indicate similar or different cell functions.
The analysis occurs at speeds of up to 1000 cells/sec so a large number of cells can be analyzed in a very short time. The results thus obtained can then be evaluated further with a specialized computer program. Unfortunately the cells are not preserved after using this technique so we can sample what is happening in a population of immune cells in MS but we cannot use the analyzed cells again. This limits our ability to investigate the function of a cell population repeatedly.
WHY A CELL SORTER?
The flow cytometer essentially destroys the cells which have been analyzed so that their function as live cells cannot be investigated further. The cell sorter works on a similar principle to the flow cytometer but only surface molecules can be interrogated so as to preserve the cells. We can then react a population of cells with a panel of antibodies, each with its own specific fluorochrome. We pass the cells through the flow channel but now we program the sorter to separate cell populations with defined characteristics of interest. So we end up for example, with one test tube of A B C and D and another with A B F and G. We can then experiment on the sorted cell populations to evaluate functional differences between them. In the case of MS we can determine whether a specific immune cell population is functioning normally or not before or after manipulation of a defined condition. This can give us insights on what goes wrong in these cells in MS.
The technique can also be modified to put a single characterized cell in a single well on a plate so that we can analyze gene function and gene regulation in individual cells derived from a population of cells. This is a powerful and enormously informative technique which gives us granular detail about how each cell in a population is acting. It allows us to tie together both surface characteristics of a cell with how its genes are acting. This can also allow us to probe both the effects of genes as well as the environment on cells which may be pathogenic in MS.We currently do not have a cell sorter at MSRI. Having this piece of equipment is vitally important to allow us to probe the cause of MS as well as evaluate potential therapies. Any donation you can make, or your gift of $25, $50, $100 or more a month will make a difference to thousands of lives as this research progresses to solve the mystery of MS.