Lymphatic Fluid and Immunotherapy

Posted on February 15th, 2017

Lymph is the fluid that circulates throughout the lymphatic system. Lymph fluids transport key immune system actors called immunoglobulins and antimicrobial medium and short chain fatty acids (SCFAs) through out the body.

Chylomicrons are packets of proteins and fats originating from the gut and transported via the lymphatic system

Lipids and proteins form a major component of immune activity called a chylomicron – packets of proteins and fats – transported from the gut via the lymphatic system. Chylomicrons are incorporated into cells and, notably, neurons in the brain. Studies have shown that brain immune system reactivity was significantly decreased when chylomicron formation was blocked in the gut. [R]

The lymph is formed when the interstitial fluid (the extracellular fluid that surrounds all cells) is collected through lymph capillaries. It is then transported through lymph vessels to lymph nodes before emptying through the thoracic duct into the left or right subclavian vein, where it mixes with emulsified fats from the colon back into the blood stream. Notably, the right subclavian vein handles all flow from the head, neck and right arm. [R]

Proportions of Body Fluids

Roughly 60% of body fluids are contained inside cells – intracellular fluid (ICF) – and 40% is extracellular fluid (ECF). The ECF is 20% blood plasma transported in arteries and veins, while  80% of interstitial fluid transported through the lymphatic system.

Proportion of Body Fluids

So, the human body has roughly four times as much lymphatic fluid as it does plasma. This illustrates the importance of lymphatic fluid in the transport of immune system components and the drainage of toxins.

Since the lymph is derived from the interstitial fluid, lymphatic fluid content continually changes based on what is draining from the various tissues and where the lymphatic fluid is sampled. Lymph picks up bacteria and other pathogens and bring them to lymph nodes where they are destroyed. A major function of the lymphatic system is to distribute essential fats, especially short chain fatty acids (SCFAs) like butyric acid, from the colon to the blood and to tissues which require SCFAs to function. [R]

Lymphatic System and the Brain’s Immune Function

Recently, lymph vessels were discovered in the lining of the central nervous system and the brain, called the meninges. Studies in animals using radioactive fluids circulated through the lymph fluid shows direct interaction between brain interstitial fluids and the lymphatic fluid. Oddly, the conventional understanding has been that the brain was not connected to the body’s immune system, ie the lymphatic system. Modern findings clearly illustrate a direct connection between the brain, the lymphatic fluids, the SCFAs and other excretions of gut microbiota. [R]

Cerebral extracellular fluids drain from brain to blood across the arachnoid villi and to lymph along certain cranial nerves (primarily olfactory) and spinal nerve root ganglia. Quantification of the connection to lymph in rabbit, cat and sheep, using radiolabeled albumin as a marker of flow, indicates that a minimum of 14 to 47% of protein injected into different regions of brain or cerebrospinal fluid passes through lymph. – Cserr et all

Composition of Lymph Fluid

  1. Water – 94%
    Healthy lymphatic fluid has very similar osmolarity and electrolyte content to seawater.  Electrolytes are minerals in the body that have an electrical charge. They are also called ions. Different fluid compartment in the body have different osmolarity levels and concentrations of eletrolytes
    Approximate seawater osmolarity (mM) and electrolyte concentration
    Osm.: 1000 | Na: 460 | K: 10 | Ca2: 10 | Mg2: 53 | Cl: 540 | SO42: 27
  2. Solids – 6%
    – Proteins: Total protein content varies from 2.0-4.5% depending on where the lymph fluid is measured. Three types of proteins are found in the lymph fluid: albumin, globulin and very low levels of fibrinogen.
    – Fats: While fasting the fat content of lymph is very low. However, while consuming a fatty diet, the proportion of fats in lymph may be as high as 5-15%.  This shows the direct, immediate connection between immune fluid content and what we eat.

References

  1. Agur, Anne MR, and Arthur F. Dalley. Grant’s atlas of anatomy. Lippincott Williams & Wilkins, 2009. [R]
  2. Cserr, Helen F., Christine J. Harling‐Berg, and Paul M. Knopf. “Drainage of brain extracellular fluid into blood and deep cervical lymph and its immunological significance.” Brain pathology 2.4 (1992): 269-276. [R]
  3. Lo, Chun-Min, et al. “Mechanism of the induction of brain c-Fos-positive neurons by lipid absorption.” American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 292.1 (2007): R268-R273.