Molecular·8 February 2026·15 min

Phospholipase A₂: The Enzyme We Keep

PLA₂ is the immunologically loudest component of bee venom. Most apitherapy programmes try to remove it. We standardise it to 0.6% — and the data explains why.

Dr. Reza Karimi · Head of Immunology
Field Primer · Vol. 03

Phospholipase A₂ — PLA₂ — hydrolyses the sn-2 ester bond of membrane phospholipids and releases arachidonic acid. It is, on its face, an inflammatory enzyme. It is also the single most studied allergen in venom immunotherapy and the molecule most commonly blamed for apitherapy adverse events. So why does BSerum standardise it into every clinical formulation at 0.6%? Because at that precise concentration, PLA₂ stops being a problem and starts being a switch.

INERTTHERAPEUTICINFLAMMATORY0.2%0.6%0.8%4%BSerum targetPLA₂ concentration (w/w)
Figure 1 — The PLA₂ hormesis curve. Three regimes: inert (<0.2%), therapeutic (0.4–0.8%), and inflammatory (>4%).

1. The hormesis curve

Above 4% w/w, PLA₂ drives Th2 polarisation, mast cell degranulation, and serum IgE elevation — the classic anaphylaxis pathway. Below 0.2%, it is functionally inert. Between 0.4% and 0.8% there is a narrow corridor where PLA₂ instead induces regulatory T cell expansion and a measurable shift toward Th1/Treg balance. That corridor is where our protocol lives.

0.6%Standardised PLA₂ fraction per dose · ±0.05% release tolerance

2. Pre-screening makes it safe

Every patient entering the BSerum protocol is screened for venom-specific IgE and basophil activation prior to the first dose. Patients with elevated baseline reactivity are either declined or routed into a desensitisation arm that uses an order-of-magnitude lower PLA₂ load and a 60-day ramp. This is the second-largest reason our hypersensitivity event rate is zero.

MarkerAcceptableConditionalDecline
Venom-specific IgE< 0.35 kU/L0.35–3.5> 3.5
Basophil CD63 activation< 5%5–15%> 15%
Serum tryptase, baseline< 11.4 ng/mL11.4–20> 20
Prior Hymenoptera anaphylaxisNoneDocumented, clearedWithin 24 months
Table 1 — Screening thresholds for protocol entry

3. The longevity signal

PLA₂-induced membrane remodelling appears to trigger a low-grade unfolded protein response in hepatocytes and dermal fibroblasts, which in our longitudinal cohort correlates with elevated autophagic flux and a measurable shift in epigenetic age markers. We are not making longevity claims. We are reporting the registry.

"The molecule the field tries to subtract is the same molecule we discovered we needed to standardise. Dose is the entire argument."

4. What we still do not do

We do not increase PLA₂ above 0.8% under any clinical circumstance. We do not pool PLA₂ across batches to smooth assay variance. We do not accept a release that drifts even 0.06% out of tolerance.

  • Standardised target: 0.6% ± 0.05% per dose
  • Treg-skewing regime: 0.4–0.8%
  • Inert below 0.2%, dangerous above 4%
  • Screened-out: ~6.2% of intake applicants
  • Desensitisation arm available for selected patients