A layered framework for immune function

Immune Function
Requires Architecture.

Immune responses succeed when tissue surveillance, recruitment, and effector execution remain coordinated. Disease emerges when that architecture breaks down, and therapies often fail when they target the final effector layer without restoring the systems beneath it.

Layer 1 maintains tissue surveillance and immune balance.
Layer 2 recruits and coordinates immune response.
Layer 3 executes adaptive, antigen-specific immunity.
Explore the thesis
Evolutionary strata
0
Cell-autonomous defense
1a
Innate tissue regulation
1b
Innate lymphoid response
2
Recruited effector immunity
3
Adaptive immunity
3i
Architectural Infrastructure
01 — The thesis

Immunity requires organization,
not just activation.

Modern immunology often describes immune responses by their parts: targets, pathways, cytokines, checkpoints, and effector cells. Immune Architecture asks a different question: how are these modules organized spatiotemporally during a normal immune response?

The framework proposes that immunity operates in layers. Foundational tissue surveillance and repair systems support recruitment and coordination, which in turn support adaptive effector function and memory.

This matters because efficient immune responses require ordered propagation across layers. Many therapies address function at the effector layer without restoring the supportive signals and tissue states that underlie durable immune control.

"Immune responses unfold in the same order immunity evolved."

Geological rock strata showing distinct horizontal layers
The geological analogy

When you look at a rock face, you see time made visible. The deepest layers are the oldest — laid down first, compressed by everything above. The newest layers sit at the surface, but they couldn't exist without the foundation beneath.

Unlike geology, all immune layers remain active simultaneously. They do not replace each other. They relay — each dependent on the integrity of what lies beneath.

ReactFoundational tissue sensing
RecruitCoordinated immune entry
RememberAdaptive effector selection
The operating principle
Evolutionary history becomes
response order.

The architecture of immunity is not only evolutionary. It is operational. During an immune response, activation proceeds through the layers in the same order they emerged evolutionarily.

Ancient tissue and cell-intrinsic defense programs react first. More recently evolved systems are recruited later, escalating the response toward adaptive specialization, effector selection, and memory.

React

Immediate tissue sensing and local immune response. Ancient defense systems detect disruption and initiate rapid protective programs.

Layer 0 / Layer 1

Recruit

Local alarm signals mobilize broader immune participation across tissues, turning local detection into coordinated effector immunity.

Layer 2

Remember

Adaptive effector selection and immunological memory refine future responses through specialization, persistence, and recall.

Layer 3
02 — The layers

Most therapies target the top. Durable immunity depends on the stack.

Scroll to deposit each layer — foundational tissue defense first, adaptive execution last. The model highlights why Layer 3 therapies often require intact Layer 1 and Layer 2 support.

Layer 3
~450 million yrs
Adaptive immunity
Antigen-specific, clonally expandable and long-lived. The vertebrate innovation that enables immunological memory.
Layer 3i
~350–450 million yrs
Architectural Infrastructure
Builds and maintains the structures that support development, education and co-ordination of adaptive immunity.
Layer 2
~450–500 million yrs
Recruited effector immunity
Translates innate alarm signals into recruited effector responses. Non-specific, but directionally instructed by the layers beneath.
Layer 1b
~600–800 million yrs
Innate lymphoid response
Tissue-resident sentinels that integrate local alarm signals and bridge innate detection to downstream orchestration.
Layer 1a
~600–800 million yrs
Innate tissue regulation
Rapid detection of threat and tissue disruption. Pattern recognition drives both pathogen alarm and protection of host tissue from immune-mediated damage.
Layer 0
~1–3.5 billion yrs
Cell-autonomous defense
Universal across all life. Every cell contains its own intrinsic defense machinery — the oldest immunity there is.
Scroll to reveal layers
Most recent
Architectural
Most ancient
03 — Functional axes

Four functions determine whether immunity becomes
protective, chronic, or ineffective

Each layer contributes to four core functions. Disease can arise when any one function is overactive, underactive, spatially misplaced, or poorly relayed to the next layer. This makes the framework useful not only as a map of immune evolution, but as a way to interpret pathology and therapeutic opportunity.

Scanning electron microscope image of a Natural Killer cell, pseudo-colored, showing characteristic surface projections

Natural killer cell — scanning electron microscopy · NIAID / NIH · Free to use under Unsplash License

I
Threat elimination

Detect and destroy pathogens, damaged cells, and aberrant tissue. The most ancient imperative.

II
Tissue restitution

Repair structural damage and restore tissue homeostasis after a response has run its course.

III
Response tuning

Calibrate the magnitude, specificity, and duration of the response to match the threat.

IV
Response resolution

Terminate active responses and return the system to baseline. Requires successful escalation through higher layers; failure here drives chronic inflammation and fibrotic disease.

Benjamin C. Harman, PhD
Benjamin C. Harman, PhD
BCH Consulting
BHarman@BCHSci.com
The scientist

Two decades at the intersection of
basic biology and translational medicine

Scientific consultant with a background spanning human evolutionary biology, developmental immunology, and immuno-oncology drug development. The layered immunity framework emerged from two decades of work at the intersection of basic immune biology and translational medicine — an attempt to build a unified architecture that is both mechanistically rigorous and clinically actionable.

Previously Senior Director of Immunology at a clinical-stage biotechnology company, where he led the development of novel immunological therapeutics from concept to IND. Now working independently through BCH Consulting, providing target prioritization, disease area strategy, and scientific advisory services to biotech and pharma.

Author of peer-reviewed publications in developmental immunology, translational medicine, and tumor immunology. Named inventor on granted patents in oncology.

04 — Therapeutic logic

Durable therapeutic responses require
the restoration of immune architecture

Checkpoint inhibitors, targeted therapies, ADCs, and T-cell redirectors can produce profound responses, but many depend on a permissive immune environment. When tumors are immune-excluded, myeloid-dominated, fibrotic, or spatially disorganized, Layer 3 pressure alone may be insufficient.

Immune Architecture reframes these failures as breakdowns in tissue surveillance, recruitment, coordination, or relay. The opportunity is to pair effector therapies with interventions that rebuild the conditions required for durable immunity.

Autoimmunity Tumor immunology Chronic inflammation Immunodeficiency Inflammaging Neuroinflammation
01

Failures become diagnosable. Cold tumors, chronic inflammation, fibrosis, and autoimmunity can be interpreted as breakdowns in specific layer functions or relay points.

02

Therapeutic strategy becomes layered. Understanding the cause of immune dysfunction in the context of the layer in which it operates assists the rational selection of disease-relevant therapeutic targets.

03

Combination logic becomes clearer. Layer 3 therapies may work best when paired with approaches that restore Layer 1 surveillance and Layer 2 recruitment.

04

The model generates predictions. Spatial biology, immune phenotyping, and tissue-state biomarkers can test whether architectural restoration improves response depth and durability.

H&E histology section showing tumor immune infiltration

Reprinted with permission · Clinical & Translational Immunology 2022

Get in touch

Interested in applying the framework?

Immune Architecture is being developed as a scientific and translational framework for interpreting immune dysfunction, prioritizing targets, and designing more durable therapeutic strategies in oncology, autoimmunity, and chronic inflammatory disease.

BHarman@BCHSci.com