Tuesday 15, July 2025

Immune System Function, Conditions & Disorders

The immune system is a network of cells, tissues, & organs that defends the body against harmful microorganisms and abnormal cells. It distinguishes between the body’s own healthy tissues and potentially dangerous invaders, such as bacteria, viruses, fungi, and parasites.

This system operates through two primary mechanisms:

Innate immunity provides an immediate, nonspecific defense against foreign substances.
Adaptive immunity develops a targeted response after exposure to specific pathogens and retains memory of them for faster responses in the future.

Key components of the immune system include:

White blood cells (leukocytes), such as neutrophils, lymphocytes (T cells and B cells), monocytes, eosinophils, and basophils, circulate in blood and lymphatic fluid to identify and neutralize threats.
Lymphoid organs, including the bone marrow (where immune cells are produced), thymus (where T cells mature), spleen (filters blood and supports immune response), and lymph nodes (filter lymph and trap pathogens).
Barriers, such as skin, mucous membranes, and stomach acid, serve as the body’s first line of defense.

How Does the Immune System Work?

The immune system identifies harmful agents such as viruses, bacteria, and toxins by recognizing molecules (antigens) on their surface that are generally not present in the body.
Innate immune cells (macrophages and neutrophils) act as the first responders, quickly attacking foreign invaders at the site of entry.
These cells release chemical signals (cytokines) that trigger inflammation & recruit more immune cells to the affected area.
Dendritic cells capture antigens & present them to T cells, linking the innate & adaptive immune responses.
Helper T cells (CD4+) coordinate the immune response by activating other cells, including B cells & cytotoxic T cells.
B cells produce antibodies to specifically bind to antigens, marking them for destruction or neutralizing them directly.
Cytotoxic T cells (CD8+) target and destroy infected or abnormal cells, including cancer cells.
After clearing the infection, some T and B cells become memory cells, allowing the body to mount a faster & stronger response if the same pathogen returns.
Regulatory T cells help shut down the immune response once the threat is eliminated, preventing unnecessary tissue damage.

Difference Between Innate Immunity vs. Acquired Immunity

Innate immunity is the body’s first line of defense and is present from birth. It provides a rapid but nonspecific response to a broad range of pathogens. This system includes physical barriers, like skin, mucous membranes, and protective secretions (e.g., mucus, stomach acid), as well as cellular defenses, including neutrophils, macrophages, and natural killer (NK) cells.

These cells identify general danger signals and respond immediately, but do not retain memory of past infections.

Acquired (or adaptive) immunity develops over time as the body is exposed to specific pathogens. Unlike innate immunity, this system generates targeted responses tailored to each unique invader. It relies on lymphocytes, specifically T cells and B cells.

B cells produce antibodies to bind to specific antigens, while T cells help coordinate the response or directly kill infected cells. One of the key features of adaptive immunity is immunological memory, which enables faster and more effective reactions upon re-exposure to the same pathogen, thereby forming the basis for long-term protection through vaccines.

Both systems work in coordination. The innate system responds first and often contains the infection, while also activating and guiding the adaptive system for a more precise and lasting defense.

When the Immune System Goes Off Track

Several health conditions can arise when the immune system becomes underactive, overactive, or misdirected. These disorders are typically grouped into three main categories:

Immunodeficiency refers to a weakened immune response. It can be inherited (primary) or acquired (secondary). Primary conditions include rare genetic disorders where parts of the immune system are missing or non-functional.

Acquired immunodeficiencies are more common and can result from illnesses like HIV/AIDS, cancer treatments like chemotherapy, or long-term use of immunosuppressive drugs. Individuals with immunodeficiency are more susceptible to persistent, severe, or unusual infections.

Autoimmune diseases are the result of immune system mistakenly targets the body's own healthy tissues. Conditions like rheumatoid arthritis, lupus, multiple sclerosis, and type 1 diabetes involve chronic inflammation and tissue damage.

The causes are not properly understood but often involve a combination of genetic, hormonal, & environmental triggers.Hypersensitivity reactions are exaggerated immune responses to typically harmless substances. Allergies to pollen, food, or medications fall under this category. These reactions range from mild skin irritation to severe, life-threatening anaphylaxis.

In other forms of hypersensitivity, such as asthma and eczema, the immune system plays a role in the development of chronic inflammatory conditions.

Common Symptoms of Immune System Disorders

Frequent or recurring infections
Slow wound healing
Persistent fatigue
Unexplained weight loss
Swollen lymph nodes
Skin rashes or inflammation
Joint pain or stiffness
Digestive issues (e.g., diarrhea, bloating)
Chronic sinus or respiratory infections
Fever without a clear cause
Sensitivity to sunlight
Numbness or tingling in hands and feet

Tests to Evaluate Immune System Health

Complete blood count (CBC)
Immunoglobulin levels (IgG, IgA, IgM)
T-cell and B-cell counts
Lymphocyte subset panel
Antibody response to vaccines
Complement system tests (C3, C4)
Autoantibody tests (e.g., ANA, rheumatoid factor)
HIV test
C-reactive protein (CRP)
Erythrocyte sedimentation rate (ESR)

How to Support Your Immune System Naturally

Maintain a balanced, nutrient-rich diet by focusing on whole foods which includes fruits, vegetables, legumes, nuts, whole grains, and seeds. Include sources rich in vitamins A, C, D, and E, as well as zinc and selenium, which support immune cell function.
Get adequate sleep every night: Aim for 7–9 hours of quality sleep. Poor or inconsistent sleep can reduce the activity of infection-fighting cells, such as natural killer cells and T cells.
Engage in regular physical activity: Moderate exercise, including walking, cycling, or yoga, improves circulation, reduces inflammation, and helps immune cells move more efficiently throughout the body.
Manage stress effectively: Chronic stress leads to a prolonged elevation of cortisol, which suppresses the immune response. Practice relaxation techniques like deep breathing, yoga mindfulness, meditation, or journaling.
Stay hydrated: Proper hydration ensures that lymph—the fluid that carries immune cells—flows freely throughout the body.
Limit alcohol and avoid tobacco: Excessive alcohol & smoking impair the immune system's ability to defend against pathogens and increase vulnerability to respiratory infections.
Get enough sunlight: Vitamin D helps regulate immune responses. Spend some time in the sun daily, or consider dietary sources like fortified foods and fatty fish if sunlight exposure is limited.
Prioritize hygiene and vaccinations: While not "natural" in the alternative sense, routine vaccinations and good hygiene practices, such as regular hand washing, are essential to supporting overall immune function.
Avoid overly restrictive diets: Severely cutting calories or eliminating major food groups can compromise your immune system by limiting necessary nutrients. Eat consistently and include variety.

Your Journey to Better Health Starts Here

At Sterling Hospital, we're dedicated to being your trusted partner in achieving better health across Gujarat. We prioritize your comfort and well-being every step of the way, providing the utmost care throughout your journey to a healthier life.

Contact Sterling Hospital today to schedule a consultation and embark on a healthier future.