Neuroimmunology

For most of the twentieth century the brain was described as immune-privileged, and the disease's immune component was assumed to be resident: microglia, behaving badly. The neuroimmunology in this corpus is largely an argument against that framing — not that microglia are innocent, but that treating the brain's immune problem as brain-local mistakes a systemic failure for a parenchymal one.

Protective autoimmunity

Schwartz (submission 84) supplies the corpus's strongest statement of the peripheral case. The protective autoimmunity hypothesis holds that Alzheimer's disease is fundamentally a failure of brain–immune communication, driven by systemic immune exhaustion — and that the therapeutic move is therefore counter-intuitive: break immune tolerance rather than suppress inflammation.

The proposed chain runs PD-L1 checkpoint blockade → rejuvenation of exhausted peripheral T cells → IFN-γ release → re-opening of the choroid plexus gateway → recruitment of MSR1⁺ monocyte-derived macrophages into the brain, which clear what resident microglia no longer can.

Two things make this notable in context. First, it inverts the field's anti-inflammatory instinct: the deficit is not too much immunity but too little of the right kind, arriving through a gate that has closed. Second, it names a gate — the choroid plexus — which the corpus has since treated as an organ in its own right rather than a conduit, grading it as amplifier rather than initiator.

Where it meets the microglial account

The corpus's Phase II thesis locates the lesion in the loss of the TGF-β/SMAD-maintained homeostatic microglial state, from which cells enter post-homeostatic trajectories pivoting through TREM2. That is a parenchymal story. Schwartz's is a peripheral one. They are not rivals so much as two ends of one axis: if the resident population is exhausted or corrupted, the question of whether reinforcements can still arrive becomes load-bearing.

The corpus's own coverage audit lists the periphery among the terms its three-phase architecture has no proper slot for — which makes this concept one of the places where the framework is knowingly incomplete rather than confidently settled.

Other immune lines in the corpus

• Complement as the effector of synaptic pruning, and C4d/LilrB2 as a cell-autonomous route to the same end.
• The NLRP3 inflammasome, graded across several papers as amplifier rather than initiator — best-evidenced is not the same as most-important.
• Trained innate immunity, where a BCG-induced glycolytic shift is argued to restore lysosomal acidification.
• Regulatory T cells, graded as a context-dependent rheostat, net protective.

Related

Glial Biology · Immunometabolism · Trained Immunity · Homeostatic Microglial Collapse · Phagocytic Clearance · Neuroimmune Interface