| My dog's illness has brought both the gastrointestinal and immune systems into my awareness and close to my heart :) . I found that in order to understand what went wrong, I needed to first understand how it should be. Here's a little immune system primer I wrote for Luna and me. I hope it will be helpful. This is gonna be a long one.............
The immune system is the head honcho of the healing process. It's task is to make a distinction between things that are "self" (naturally belonging in the body) and those that are "non-self" (foreign or otherwise harmful material) and to act by neutralizing or destroying that which is "non-self". The immune system is unlike other bodily systems because it is not a group of physical structures but rather a system of complex interactions involving many different organs, structures and substances that include white blood cells, bone marrow, lymphatic vessels and organs, specialized cells found in body tissues and specialized substances (serum factors) that are present in the blood. In a perfect world, all of these components work together to protect the body against infection and disease. Like everything else in life, the immune system can only be as strong as it's weakest point. If weak point(s) exist, they can be either congenital (hereditary) or acquired (introduced into the body).
The immune system is functional at birth, but is limited in function to what the dam has passed on during gestation. Immunity present at birth is called innate immunity. Immune function develops as the body matures and learns to defend itself against a variety of foreign invaders (antigens). This is called adaptive immunity. All cells of the immune system originate in the bone marrow and some remain and mature there (B cells, NK cells) and some leave the bone marrow and mature elsewhere in the body (T cells). The immune system has the ability to learn to identify and remember specific antigens that have been encountered. This is accomplished by two basic means, cell-mediated immunity and humoral immunity.
Cell-mediated immunity is comprised of white blood cells called T-lymphocytes (T cells) that identify and then destroy cancerous cells, viruses and microorganisms like bacteria and fungi. T cells mature in the thymus gland, where they are programmed to identify one particular type of invading enemy. Not all white blood cells that apply for the job make it through the thymus, though, they have to pass a test first. If the programming is imperfect and they misidentify "self" as "nonself", they are eliminated. Once the T cells are deemed worthy, they are released into the blood stream on a seek and destroy mission of the antigens that correspond with their programming by secreting proteins called cytokines. They also alert B cells (next paragraph) to produce antibodies. I personally find the thymus incredibly amazing and it has made me realize what a very important little detail in the immune system it is. I have also read that the thymus activity begins to bow out with maturity and the management of immune system gradually shifts to the lymph glands, the spleen and the bone marrow. This in particular perked my ears up because it seems to correspond with the problem some older puppies have with weakened immune systems. It may be a lapse in the "changing of the guard" from thymus to the other organ systems that will self-correct, which I suspect is why vets aren't initially overly concerned about it.
Humoral immunity is comprised of white blood cells called B-lymphocytes (B cells) that are involved in the production of antibodies. The antibodies produced are proteins formed to match the surfaces of specific antigens and when those antigens are encountered, the antibodies either damage the invasive cells or alert the white blood cells to attack. When a B cell is presented with a particular antigen, it engineers an antibody to match it and stores a blueprint of the invader in case of subsequent exposure. B cells are manufactured and mature in the bone marrow and come complete with the ability to produce an almost infinite variety of antibodies, so it can match whatever antigen it is presented with. Talk about flexible! This ability is known as "jumping genes", because inside the B cells the genes that determine the chemical structure of the protein to be produced can be shuffled into vast numbers of different combinations enabling it to take on virtually any foreign invader. Humoral immunity is the phenomenon that makes immunization possible.
White blood cells are made from stem cells (embryonic cells that can mature into any type of cell) and are the body's first line of defense against invaders and their ability to move independently in the bloodstream and even pass through cell walls enable them to travel quickly to wherever in the body they are needed. Briefly, :D (are ya still with me?), there are different categories of white blood cells, and each performs a specific function:
Granulocytes - Three types: Neutrophils ingest and destroy bacteria; Eosinophils ingest and destroy antigen-antibody combinations (that's when B cells damage antigens) and moderating allergic reactions by secreting an enzyme that breaks down histamine; and Basophils which secrete heparin or histamine in response to antigens.
Lymphocytes - Three important types: T cells play a major role in cell-mediated immunity; B cells are responsible for production of antibodies; NK (natural killer) cells destroy body cells that are infected or become cancerous.
Monocytes - These are the garbage collectors. They digest foreign particles along with damaged, aging or tumor cells. They circulate in the bloodstream for a day or so and then enter the tissues and clean up there, where they acquire a new name, macrophages.
We all know how important general maintenance is in life :) , and this is where the lymphatic system provides a kind of continuous cleansing on the cellular level, draining fluids from the spaces between cells and carrying waste products, toxins and other debris from the tissues and filtering it through the lymph nodes, where undesirables are removed and the macrophages make short work of them. The rest is returned to circulation. The spleen filters the blood and removes red blood cells that need replacing. It is also the "classroom" where antigens are brought to the B cells so they can manufacture an appropriate response.
This is an incredibly comprehensive system, so how in the heck do we take care of it and what do we do when things go wrong? Maintenance, prevention and intervention only if the system goes awry. Maintenance is providing the full-spectrum of nutrients necessary to the body and prevention would be avoiding unnecessary exposure to things that depress it, such as an overabundance of chemicals, pesticides, certain food additives and other environmental factors, as well as stress.
For people who want to incorporate herbal or homeopathic remedies that support the immune system, it's important to learn about what kind of response the remedy triggers before thinking it could never be harmful, especially if you have a dog with an existing immune dysfunction. The same holds true for conventional treatment as well, but people tend to know that and feel an herbal or homeopathic approach can have no negative consequence and that if it doesn't work, at least it will have done no harm. I'm not convinced that's a fact. Having a dog with a compromised immune condition has taught me that often the best road to health can be found by backing up a step or two and simplifying exposure rather than adding more to the mix and complicating it further. It's also important to remember that the right amount of anything is the optimum amount whether it's a drug or an herb or a nutrient, and if a little is good it doesn't necessarily follow that more is better.
That's all, folks! :D  |