1 Why Focus on Phagocytes? Phagocytes— these are macrophages, neutrophils, dendritic cells (DCs), monocytes and a handful of “special teams” such as eosinophils and Langerhans cells—constitute the professional ingesters of the immune repertoire.  They provide (i) first-contact host defence, (ii) orchestration of downstream adaptive immunity, and (iii) cleanup and repair after inflammation.  They are therefore both sentinels and governors of immune homeostasis.   2 Developmental Origins […]

1 Conceptual Genesis & Terminology These four classes underlie the stranger (PAMP), danger (DAMP) and altered-self (antigen/hapten) paradigms that collectively choreograph innate–adaptive crosstalk. 2 Antigens Sub-topic Concepts Mechanistic/structural highlights 2.1 Chemical & physical determinants Size (> 5 kDa), chemical complexity (heteropolymers > homopolymers), tertiary structure, foreignness and degradability govern immunogenicity. Repetition of a single sugar on bacterial polysaccharide engages BCRs avidly but impairs […]

1 Overview: Why “Barrier Immunity”? Before a pathogen confronts circulating leukocytes it must first traverse multilayered defenses that are physical (structural), chemical (molecular) and cellular (sentinel-cell) barriers.  These barriers are evolutionarily ancient, encode tissue specificity and are continuously remodelled by commensal microbiota, neural inputs and systemic cytokines.  Failure at any tier precipitates infection, allergy or autoinflammation.   2 Physical Barriers Level […]

1  Conceptual Framework Immunity is organized into two inter-locking layers that share evolutionary continuity yet exhibit distinct kinetics, receptor usage and memory capacity. 2  Innate Immunity Theme Details Selected mechanistic highlights 2.1 Cellular sentinels Tissue-resident macrophages, dendritic cells (DCs), γδ T cells, innate lymphoid cells (ILCs) and epithelia form a layered surveillance network. Ontogeny ranges from yolk-sac–derived, […]

Introduction and Classification Natural Killer (NK) cells represent a category of cytotoxic lymphocytes primarily associated with the innate immune system while exhibiting functionalities that bridge innate and adaptive immunity. Classified as unconventional lymphocytes and members of the innate lymphoid cell (ILC) family, specifically Group 1 ILCs, NK cells constitute a principal effector population capable of […]

Main Definion of B Lymphocytes B lymphocytes are some of the most important cells of the immune system, especially in specific immunity. Together with T lymphocytes, they form the basis of the body’s protective barrier. They can very precisely recognize antigens using special “sensors” on their surface – B cell receptors (BCR for short). The […]

1. Identity and Core Task 2. Developmental Pathway in the Thymus 3. Antigen Recognition Architecture 4. Activation of Naïve CD8⁺ T Cells Signal Delivered by Outcome if Absent Notes 1. TCR engagement Peptide–MHC-I on dendritic cells No activation CD8 co-receptor stabilizes binding 2. Costimulation CD80/CD86 on DC ↔ CD28 on T cell Anergy or deletion […]

T helper (Th) cells, also referred to as CD4⁺ T lymphocytes, are a specialized subset of adaptive immune cells that play a pivotal role in coordinating immune responses. Their primary function is to regulate the activity of other immune cells—most notably B cells, cytotoxic T lymphocytes, macrophages, and innate lymphoid cells—through direct cell–cell interactions and […]