Immunology explores our immune system, a complex and structured network of molecular and cellular components that exploits our immunity, the front-line of defence against external molecules and pathogens.
The immune system is composed of innate and adaptive immunity . The former is non-specific but continuously tackles all potential pathogens that enter our body. It includes physical barriers (like skin and saliva) and various cells. These mechanisms protect our body and fight any infection in the first instance. If the innate immunity defence mechanism is unable to clear off the pathogen(s) from our body, the adaptive immunity acts as the second line of defence and gets activated. This second line of defence includes recruitment of two different groups of specialised cells: B and T lymphocytes. B lymphocytes are known to produce antibodies, molecules that can target specific pathogens, especially those that circulate freely in the bloodstream. Activated T lymphocytes will chase bacteria and viruses that have colonised our tissues and will remove infected cells and de facto, the pathogen(s). The adaptive immunity also maintains the memory of encountered infections, enabling it to act swiftly and effectively if it recurs. The mechanistic action of vaccines is based on harnessing this aspect of our innate and adaptive immunity. The objective here is to prime the body allowing it to respond rapidly following exposure to a pathogen, thereby destroying it without causing the disease.
Inability of our immune system to perform at its optimal levels could result in the development of some serious pathologies. For example, allergies are a consequence of imbalanced immune system that develops when the immune system reacts to harmless foreign substances (like pollens, dust, or certain types of food) releasing potent chemicals triggering an allergic reaction . A mild reaction may result in hay fever or skin rash, with minimal impact on the quality of life. However, asthma is a debilitating disease of the airways that occurs when the immune cells react to inhaled particles, causing tissue damage over extended period. It is a major cause of illness, sometime fatal, and is particularly prevalent in children. Anaphylaxis, the unpredictable abnormal immune response to an external substance, is usually fatal .
Sepsis is another potential life-threatening condition usually triggered by microbial infection. This leads to dysregulated immune system resulting in activation of systemic immune responses and hyper activation of immune cells producing pro-inflammatory cytokines and chemokines. The resultant effect can be quite serious with the patient needing immediate treatment in an intensive care including intravenous fluids to regulate blood pressure, supported ventilation and antibiotics to fight bacterial infection.
Similarly, some viruses (like SARS/MERS coronaviruses or influenza) could drive our immune system to over-reactive state resulting in a systemic failure called “cytokine storm” . Cytokines are small molecules released by cells, including immune cells, used to activate our body’s response against infection. However, like in the Covid-19 pandemic, the SARS-CoV-2 virus infection leads to a hyperactive and impaired immune system resulting in a state of excessive inflammation. This could be of serious consequences and even fatal.
In summary, these are just a few examples that suggests it is extremely challenging to understand the complete biology of our immune system. Despite the enormous progress made since the first vaccine was pioneered by Edward Jenner in the 18th Century, immunology is still fascinating and challenging us to discover the inner secrets of our immune system. Indeed, to further extend our understanding into this fascinating frontier we will need to continually develop novel assays. This would allow us to continue our quest in identifying novel therapies, possibly personalised therapies, to tackle immune-related diseases.
- Parkin J and Cohen B. Lancet. 2001
- Galli SJ et al. Nature. 2008
- Jose JR et al. The Lancet Respiratory Medicine. 2020.
1. B lymphocytes IgE release assay
2. Cell Adhesion
Cell adhesion is a complex biological process that involves receptor-ligand interactions, changes in intracellular signalling pathways and cytoskeletal rearrangement.
Attachment of cells to specific extracellular matrix component is essential for cell growth, survival, and cellular interactions. Adhesion assays are often employed to evaluate the ability of cells to adhere to specific substrates in the presence or absence of specific inhibitors. Overall, this assay has applications to understand the underlying mechanisms in cancer metastasis.
3. Cell Migration
Cell migration is a key physiological process that regulates immune response, inflammatory signals and cancer metastasis. Transwell cell migration evaluates the ability of single cells to migrate towards a chemotactic gradient including chemokines, growth factors.
These assays can be employed to understand key regulators of cell migration such as the Rho family of small GTPases
4. Effect of LPS stimulation on TNFα release from M1 polarized macrophages
5. FACS characterisation of primary T cell populations
6. FACS-based analysis
7. Macrophage Phagocytosis
THP-1 stimulation by PMA and cytokine release
Quantification of different analytes following THP-1 stimulation by PMA for 72 hours. Data expressed as mean ± SEM
8. Peripheral blood mononuclear cells (PBMCs) – anti-CD3/anti-CD28 stimulation
9. Peripheral blood mononuclear cells (PBMCs) – anti-CD3 stimulation
10. Primary T cells – Inflammatory stimulation
11. Scratch Wound Healing
In vitro scratch wound assay, also termed as wound healing assay, is a well developed and validated method to gain a better understanding of cell matrix, cellular interactions, and cell migration. Basically, the process involves creating a ‘scratch’ in a cell monolayer mimicking a wound model in vitro. The rate of cell migration/proliferation is then measured by capturing images at regular intervals and is represented as ‘wound or gap closure’.
This process of collective cell migration is also termed ‘sheet migration’. This is observed in various processes including cancer metastasis, tissue injury/regeneration and embryonic development. This assay can be performed under different conditions including cells treated with different compounds, RNA knock-down or by altering the constituents of the extra cellular matrix. Scratch wound assay can be easily adapted for medium to high throughput applications.