Saturday, December 20, 2008

Rituxan, B cell depletion therapy proved efficacious again!

Rituxan (MabThera in Europe) has again been found to significantly reduce symptoms of autoimmune disease. The newest clinical trial results are for Rheumatoid Arthritis. Previously it has been found to be helpful for MS and Lupus. Read the new clinical trials article here:

B cells are our memory cells and they are the cells that produce antibodies. They are a kind of white blood cell. We have tens of millions of them in our body especially in the dry skin (epidermis) lining the outside of our body and the wet skin (mucous membrane) that lines the inside of our mouths, throats, intestinal tract, nasal passages, and the "plumbing tubes" or our urinary and sexual organs--urethra, ureters, vagina, uterus, fallopian tubes.

Immature B cells are being constantly produced in our bone marrow and released into the body where they mature. They are a vital part of our immune system. Without them we would quickly die of infection. As they mature they develop a CD 20 protein/receptor on their surface. Rituxan attaches to this receptor and labels the B cell for death. Other immune cells then kill the B cells. Good news is immature B cells do not have this receptor and are not killed by Rituxan. Given time (months) they mature and take the place of all the mature B cells killed by Rituxan.

The B cells lining the "outside" surfaces of our body both dry and wet work closely with another kind of stationary white blood cell called a mast cell of which equal million are found at these "outside" surfaces. The B cells produce antibodies and cytokines which can activate mast cells resulting in destruction of foreign pathogens (good) or destruction of patients own tissues (bad). The destruction of your own tissues is called autoimmune disease.

B cell are intimately involved in the autoimmune process in another way as well. They are the source of autoantibodies which independently attack “self” tissues while labeling those tissues for futher attack by dendritic and T effector cells. Some of our B cells are"bad" B cells. These B cells keep the autoimmune "pot" at constant "boil" by producing the autoantibodies. When the B cells are depleted with Rituxan or other B cell depleting medicines the autoantibodies are eliminated, in most cases the autoimmune disease stops. That is the good news.

The bad news is the only med FDA approved so far is Rituxan aka MabThera. It destroys all B cells including the ones that make and remember the antibodies to childhood diseases like measles and chicken pox. When all B cells are destroyed with this kind of med, the patient is no longer immune to a whole host of disease that the patient formerly was immune to. Viruses are a special problem. The patient may need a new set of child hood vaccinations after B cell depletion therapy.

More bad news, many of us carry hidden, suppressed viruses inside our bodies including herpes that causes cold sores, JC virus (jvc), CMV (Cytolomegalovirus) and worst of all the PML virus. PML stands for Progressive Multifocal Leucoencephalopathy. Without B cells these viruses can become reactivated. PML is especially bad. It can become an untreatable brain infection that is almost always fatal. No one can predict who will get PML after a Rituxan infusion. The incidence is quit low less than one in a thousand but it is a very horrible potential consequence of Rituxan.

Hopefully future research will allow only autoimmune antibody producing B cells to be destroyed eliminating the danger of PML and the need for re-vaccination for childhood disease of patients who are infused with B cell depletion drugs.

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