Immunomodulation in Ayurveda

The Ayurvedic Concept of Immunity

1. Vyadhikshamatva - literally "the power to resist disease." This is the Ayurvedic equivalent of immunity. It has two components:
   • Vyadhi Bala Virodhitva - resistance to the onset of disease
   • Vyadhi Utpada Pratibandhakatva - suppression of disease after it has started
2. Ojas - considered the finest, most refined product of tissue metabolism (Dhatu Poshana). Ojas is the biological correlate of vitality and immune strength. Depleted Ojas = compromised immunity.

Rasayana - The Immunomodulatory Branch of Ayurveda

• Prolonging life (Dirghayu)
• Enhancing memory and intellect
• Freedom from disease (Niramaytva)
• Strengthening tissue quality (Dhatu Pushti)
• Resistance against environmental stress

Key Rasayana Herbs and Their Immunomodulatory Mechanisms

Molecular Mechanisms of Rasayana Immunomodulation

1. Innate Immunity Enhancement
   • Macrophage activation and increased phagocytosis
   • Natural Killer (NK) cell stimulation
   • Enhanced cytotoxic granule exocytosis
2. Adaptive Immunity Modulation
   • T-lymphocyte proliferation (Th1/Th2 balance)
   • Immunoglobulin production
   • Dendritic cell modulation
   • CD4+/CD8+ T cell ratio regulation
3. Cytokine Regulation
   • Downregulation of pro-inflammatory cytokines: TNF-α, IL-1, IL-6
   • Upregulation of anti-inflammatory cytokines: IL-10
   • Enhancement of IFN-γ and IL-2
4. NF-κB Pathway Inhibition - herbs like Guduchi and Nirgundi reduce inflammatory cytokines via this pathway
5. Psycho-Neuro-Immune Axis - Adaptogenic herbs regulate the HPA (hypothalamic-pituitary-adrenal) axis, reducing cortisol and thereby preventing immune suppression from chronic stress
6. Antioxidant Mechanisms - Reduction of reactive oxygen species (ROS) preserves immune cell integrity

Classical Formulations

• Chyavanaprash - the most famous Rasayana, built around Amalaki; enhances respiratory immunity
• Brahma Rasayana - classical rejuvenative formula
• Dhatryadi Rasayana - polyherbal with demonstrated antioxidant and immunomodulatory activity
• Triphala - combination of Amalaki, Haritaki, Vibhitaki; antioxidant and immune support
• Sudarshana Ghana Vati - used in febrile illness

Ayurvedic Principles Behind Immunomodulation

• Tridosha (Vata, Pitta, Kapha) - imbalance leads to susceptibility to disease
• Agni (digestive fire) - strong Agni produces quality Dhatus and ultimately Ojas; weak Agni generates Ama (toxins) that block immunity
• Srotas (channels) - open channels allow proper nourishment and waste removal, supporting immune vigilance
• Satva (mental purity) - mind-body connection recognized in what modern science calls psychoneuroimmunology

Recent Clinical Evidence

• Dipankar et al. (2025, Cureus) - review of Ashwagandha's immunomodulatory and neuroprotective properties [PMID: 40951251]
• Bhandari et al. (2024) - systematic review of traditional formulations including Ayurvedic herbs against COVID-19 [PMID: 37972056]
• Prakash et al. (2024, Cureus) - immunomodulatory effects of a herbo-mineral Ayurvedic formulation in experimental models [PMID: 38800281]

Summary

Pongamia glabra (Karanja / Indian Beech)

Botanical Identity

Ayurvedic Properties (Guna-Karma)

Sanskrit Synonyms

• Karanja - the most common name
• Naktamala - the tree that glows at night
• Ghritapura - rich in fatty substance
• Udakirya - dispels diseases

Parts Used and Their Applications

Phytochemistry

Flavonoids (most significant class)

• Karanjin - a furanoflavonol; the trademark compound of this species; first compound ever isolated from it
• Pongamol - a benzofuranoid flavonoid; key bioactive compound with diverse pharmacological activity
• Kanjone, Pinnatin, Pongapin - additional furanoflavones
• Lanceolatin A and B - flavanones

Other Phytochemicals

• Alkaloids - terpene alkaloids
• Tannins and polyphenols - antioxidant activity
• Fixed oils / Fatty acids - seed oil contains oleic acid (44-71%), linoleic acid (11-18%), palmitic acid, stearic acid, arachidic acid, behenic acid, eicosenoic acid
• Steroids and triterpenes - cycloartenol, β-sitosterol
• Carbohydrates and glycosides

Note: Current Science first reported the isolation of pongamol from Pongamia glabra oil; its molecular formula is C₉H₇O₂ (later revised after methoxy compound analysis).

Pharmacological Activities

1. Antifungal / Antimicrobial

2. Anti-inflammatory

3. Antidiabetic / Anti-hyperglycaemic

4. Antioxidant

5. Anticancer

6. Anthelmintic

7. Wound Healing

8. Antiviral

9. Anti-diarrhoeal

Classical Ayurvedic Uses

• Kushtha (skin diseases): Karanja oil is a primary ingredient in medicated oils for eczema, psoriasis, and fungal infections
• Krimiroga (worm infestations): Root and seed preparations
• Vrana shodhana (wound cleansing): Bark decoction washes
• Arsha (hemorrhoids): Oil applied externally; bark decoction used as sitz bath
• Netra roga (eye diseases): Young leaf decoction instilled in conjunctivitis
• Medoroga (obesity/fat disorders): Bitter tikta rasa helps reduce Kapha and medas
• Prameha (diabetes): Flowers and leaves used

Modern Formulations with Karanja

• De-Pile Ointment - external and internal hemorrhoids
• Dermasyl Skin Ointment - eczema, scabies (anti-infective)
• Dermafex Oil/Soap - eczema, psoriasis

Biofuel Application

Safety

Carbon Clearance Test

Definition and Purpose

Principle

• Kupffer cells in the liver (primary site)
• Macrophages in the spleen
• Other fixed and free macrophages of the MPS

A higher phagocytic index = more active macrophages = enhanced non-specific immunity

Animals Used

• Swiss albino mice (most common) - typically 20-30 g
• Wistar rats (less common)
• Group size: 6 animals per group (minimum)

Materials Required

Procedure (Step-by-Step)

1. Pre-treatment

• Administer the test drug/extract orally (p.o.) for 7-14 days (commonly 10 days)
• Groups:
  • Normal control (vehicle only)
  • Standard immunostimulant (e.g., Levamisole 50 mg/kg, or LPS)
  • Standard immunosuppressant (e.g., Cyclophosphamide 30 mg/kg i.p.) - used as negative control
  • Test drug at low and high doses

2. Carbon Injection

• 48 hours after the last dose, inject Indian ink (colloidal carbon) intravenously (i.v.) via the tail vein at a dose of 0.1 ml/10g body weight (or 0.3 ml/30g)

3. Blood Sampling

• T₁ = 0 minutes (immediately after injection)
• T₂ = 15 minutes after injection

4. Sample Processing

• Mix 50 µl blood with 4 ml of 0.1% sodium carbonate solution
• Sodium carbonate lyses the RBCs and releases carbon particles into solution
• Read optical density (OD) at 660-675 nm using spectrophotometer

5. At End of Experiment (Organ Weight Correction)

• Sacrifice the animals
• Weigh liver and spleen
• Record body weight
• These are used to calculate the corrected phagocytic index

Calculations

Step 1: Phagocytic Index (K)

• OD₁ = Optical density at time T₁ (0 min)
• OD₂ = Optical density at time T₂ (15 min)
• T₂ - T₁ = Time interval = 15 minutes

Step 2: Corrected Phagocytic Index / Stimulation Index (α)

• W = Body weight (grams)
• L = Liver weight (grams)
• S = Spleen weight (grams)

Interpretation:

What the Test Measures

Significance in Immunomodulatory Drug Evaluation

• Immunostimulant activity if it significantly increases the phagocytic index (K and α) vs. control
• Immunosuppressant activity if it significantly decreases the phagocytic index

• Hemagglutination (HA) titer - humoral (antibody-mediated) immunity
• Delayed Type Hypersensitivity (DTH) - cell-mediated immunity
• Neutrophil adhesion test - neutrophil function

Advantages

• Simple, inexpensive, and reproducible
• Measures functional phagocytic capacity (not just cell counts)
• Well-validated in vivo model with decades of use
• Applicable across a wide range of drug categories
• Sensitive enough to detect dose-dependent changes

Limitations

• Measures only non-specific (innate) immunity - does not evaluate adaptive immunity
• Does not distinguish between liver and spleen contribution separately
• Cannot identify molecular mechanism of action
• Requires animal subjects (ethical considerations)
• Carbon particles are not pathogens - results may not perfectly mimic infection scenarios

Examples of Drugs Tested Using Carbon Clearance

Serum Immunoglobulins

What Are Immunoglobulins?

Basic Structure of Immunoglobulins

• 2 Heavy (H) chains - identical, ~50 kDa each; determine the class (isotype)
• 2 Light (L) chains - identical, ~25 kDa each; either κ (kappa) or λ (lambda) type
• Chains are held together by inter-chain disulfide bonds and non-covalent interactions

Regions:

Enzymatic Cleavage:

• Papain cuts above the hinge → 2 Fab fragments + 1 Fc fragment
• Pepsin cuts below the hinge → 1 F(ab')₂ fragment (bivalent) + pFc' fragment

Schematic Structures of All Five Classes

The Five Classes of Serum Immunoglobulins

Properties Comparison Table

Detailed Profile of Each Class

1. IgG - The Dominant Serum Immunoglobulin

• Most abundant - accounts for 75-85% of total serum Ig
• Monomeric with a flexible hinge region
• Longest half-life - 23 days (due to FcRn neonatal Fc receptor recycling)
• Only Ig that crosses the placenta - provides passive immunity to neonate for 3-6 months
• Four subclasses (IgG1 > IgG2 > IgG3 > IgG4 in serum concentration):
  • IgG1 and IgG3: Best at complement activation and ADCC (antibody-dependent cellular cytotoxicity)
  • IgG2: Responds to polysaccharide antigens (e.g., bacterial capsules); only triggered at high antigen density
  • IgG4: Does NOT activate complement; important in allergy desensitization

• Opsonization (enhances phagocytosis)
• Complement activation (classical pathway)
• Neutralization of toxins and viruses
• ADCC via NK cells
• Neonatal passive immunity (via placenta)

• Chronic liver disease
• Subacute or chronic infections
• Connective tissue diseases (SLE, RA)
• IgG myeloma (monoclonal)

• Hypogammaglobulinemia
• X-linked agammaglobulinemia (Bruton's)
• Nephrotic syndrome (protein loss)

2. IgA - The Mucosal Guardian

• Two forms:
  • Serum IgA: Monomeric; 5-15% of serum Ig
  • Secretory IgA (SIgA): Dimeric IgA + J chain + Secretory Component (SC); found in mucosal secretions (saliva, tears, breast milk, gut, respiratory secretions)
• Secretory component protects IgA from proteolytic digestion in harsh mucosal environments
• Two subclasses: IgA1 (longer hinge, susceptible to bacterial proteases) and IgA2 (shorter hinge, more protease-resistant)

• First line of defense at mucosal surfaces (respiratory, GI, urogenital tracts)
• Neutralization of pathogens before systemic entry
• Does NOT activate complement efficiently
• Present in colostrum/breast milk - protects newborn gut

• Selective IgA deficiency (most common primary immunodeficiency) - recurrent respiratory and GI infections, increased risk of atopic disease
• Elevated in: chronic liver disease, IgA nephropathy, IgA myeloma

3. IgM - The First Responder

• Pentameric structure - 5 monomeric units held together by J chain
• Largest immunoglobulin (900 kDa)
• First antibody produced in primary immune response (before class-switching)
• Has 10 antigen-binding sites (bivalent × 5 monomers) - highly efficient agglutination
• 4 constant domains (Cμ1-4) instead of hinge region
• Complement activation: IgM undergoes a "star-to-staple" conformational change upon antigen binding, exposing C1q-binding sites

• Best complement activator (classical pathway)
• Agglutination of bacteria/RBCs
• First antibody in primary immune response (diagnostic marker of acute/recent infection)
• ABO blood group antibodies are IgM (natural isohemagglutinins)
• Rheumatoid factor (anti-IgG antibody) is usually IgM

• Elevated IgM = acute or recent infection, primary response
• Waldenström's macroglobulinemia - IgM-secreting B-cell malignancy → hyperviscosity syndrome
• Low IgM = XLA, combined immunodeficiency

4. IgD - The B-cell Regulator

• Present at very low serum concentrations (<1%)
• Has a long, flexible hinge region
• Co-expressed with IgM on the surface of mature naive B cells (as antigen receptor)
• Role in B cell activation and suppression - helps control lymphocyte activation
• May protect against microbes in the upper respiratory tract
• Some evidence for regulatory role, maintenance of B cell memory, induction of TNF-α, IL-1β

• Generally limited clinical significance
• IgD myeloma - rare plasma cell malignancy; M spike detected on serum protein electrophoresis
• Useful as marker of B-cell maturation stage

5. IgE - The Allergy Antibody

• Lowest serum concentration of all Igs (trace levels, ~0.05 mg/L)
• Monomeric with 4 constant domains (Cε1-4), no hinge region
• Most IgE is bound to high-affinity FcεRI receptors on mast cells and basophils in tissues (not free in serum)
• Cross-linking of mast cell-bound IgE by allergen triggers degranulation → histamine, prostaglandins, leukotrienes → allergic reaction
• Short half-life in serum (2-3 days) but long-lived when bound to mast cells

• Mediates type I (immediate) hypersensitivity (allergies, anaphylaxis)
• Defense against helminth (worm) parasites - via eosinophil activation (ADCC)
• Activates mast cells and basophils

• Elevated IgE = atopic diseases (asthma, eczema, allergic rhinitis), parasitic infections
• Very high IgE = Hyper-IgE syndrome (Job syndrome) - recurrent bacterial infections + eczema
• Used to monitor allergen immunotherapy response
• Measured as total IgE and allergen-specific IgE (RAST/ImmunoCAP testing)

Fc Region Interactions Summary

Isotype, Allotype, and Idiotype

Serum Protein Electrophoresis Context