Introduction

The human immune system unites innate and adaptive responses, offering immediate, non-specific protection and long-lasting, targeted defences. By integrating these layers, it combats a vast array of pathogens effectively.

Innate and Adaptive Components

Physical barriers, chemical substances, and beneficial microbes form the innate frontline. Specialised cells like neutrophils and macrophages rapidly counter threats, while the adaptive branch (B and T lymphocytes) develops highly specific responses and immune memory.

Barrier Type	Components	Primary Functions
Mechanical	Skin, mucous membranes	Blocking pathogen entry
Chemical	Enzymes, acids	Neutralising invaders
Biological	Microbiome	Outcompeting pathogens

Communication and Clinical Relevance

Cytokines and the complement system coordinate between innate and adaptive responses. This understanding drives vaccine innovation and immunotherapies, enhancing the body’s ability to prevent and overcome infections, and informing treatments for autoimmune and inflammatory conditions.

Immune-Based Interventions Include: