Endometriosis research carries a sampling constraint that most inflammatory indications do not. The circulating immune compartment in menstruating donors varies across the cycle, and the disease itself is driven by cyclical events. A cohort collected without recording cycle phase has introduced a periodic variable that cannot be reconstructed from a stored vial.
Cycle phase belongs in the required fields
Circulating lymphocyte subsets, natural killer cell cytotoxicity and monocyte activation state all show variation across the menstrual cycle in healthy women, driven by the changing estrogen and progesterone environment. In endometriosis the cyclical process is also what drives lesion activity and symptoms.
The practical consequence is that a disease cohort collected in the luteal phase compared against controls collected without regard to phase produces a difference that is partly hormonal. Cycle day at collection, or an explicit note that the donor is not cycling because of hormonal suppression or surgical menopause, is the single most valuable annotation in this indication.
Hormonal suppression is near-universal and changes everything
Standard management uses combined hormonal contraceptives, progestins, gonadotropin releasing hormone agonists or antagonists, all of which suppress cyclical hormonal variation. That is helpful for interpretation in one sense, since it removes the cycle variable, and unhelpful in another, since sex steroids modulate immune function directly.
A donor on gonadotropin releasing hormone therapy is in a hypo-oestrogenic state with measurable immune consequences. A donor on combined hormonal contraception is in a different hormonal state again. These should be recorded as distinct groups rather than pooled under a single treated label.
| Hormonal status | Cycle variation | Cohort handling |
|---|---|---|
| Naturally cycling, no hormonal therapy | Present | Record cycle day; match phase across arms |
| Combined hormonal contraceptive | Suppressed | Distinct stratum; steady hormonal state |
| Progestin only | Largely suppressed | Distinct stratum; different steroid profile |
| Gonadotropin releasing hormone agonist or antagonist | Absent, hypo-oestrogenic | Distinct stratum with clear immune effects |
| Post-surgical or menopausal | Absent | Distinct stratum; age confounding likely |
Related product
Disease-state PBMCs. PBMCs from donors with a documented diagnosis, across 24 autoimmune and inflammatory indications.
Diagnostic delay makes duration unreliable
Endometriosis is well described as carrying a long interval between symptom onset and diagnosis, frequently cited in years. That means time since diagnosis is a poor proxy for disease duration, because two donors diagnosed in the same year may have had the disease for very different lengths of time.
Where duration matters, symptom onset is a better anchor than diagnosis date, with the caveat that it is recalled rather than documented. It is worth capturing both and being explicit about which is being used.
Stage does not track symptoms, and neither should the cohort design
Surgical staging systems describe lesion extent and adhesion burden. They correlate poorly with pain severity, which is the symptom that dominates the patient experience. A donor with minimal disease by staging can have severe pain, and extensive disease can be relatively asymptomatic.
For research this means stage and symptom burden are separate variables and choosing one as the cohort axis is a decision that should be made deliberately. Studies of lesion biology may want staging; studies of pain mechanisms and central sensitisation almost certainly want symptom measures instead.
The immune phenotype is dysregulation, not classical autoimmunity
Endometriosis sits in the inflammatory rather than the autoimmune part of the catalogue. The described immune features include altered peritoneal macrophage behavior, reduced natural killer cell cytotoxicity against endometrial cells, and a shifted cytokine environment. There is no defining autoantibody and no established single autoantigen.
That shapes what peripheral blood can be expected to show. Circulating natural killer cell function, monocyte phenotype and cytokine production on stimulation are reasonable readouts. Expectations of a clean disease-defining serological marker are not supported, and a study designed around finding one should be reconsidered before material is ordered.
Specifying an endometriosis cohort
OrganaBio supplies disease-state donor material across 24 autoimmune and inflammatory indications for research use, covering discovery, drug screening and biomarker work, with a post-thaw viability specification above 80 percent. Donor-matched plasma, serum and PBMCs from the same donor are available, which most suppliers cannot provide. Donor selection can be scoped by disease state, HLA genotype, age, sex, ethnicity, blood type, CMV and EBV status, BMI and smoking status, all subject to availability.
For this indication the parameters worth naming are cycle day at collection or an explicit non-cycling status, current hormonal therapy by class, surgical stage where available, symptom burden, symptom onset as well as diagnosis date, and prior surgical history.
High-resolution NGS HLA genotyping is performed across HLA-A, HLA-B, HLA-C, HLA-DR, HLA-DQ and HLA-DP, and KIR genotyping is included in donor characterization. Where a design needs the same donor sampled more than once, the repeat-collection program covers eligible donors and is not a blanket guarantee for every donor or request.
Donor-matched plasma and serum alongside PBMCs is particularly useful in this indication, because circulating hormone levels can be measured from the matched sample and used to verify the recorded cycle phase rather than relying on the donor’s report alone.
Related material: what a mononuclear cell preparation contains, how HLA typing resolution is reported, and the cryopreserved PBMC format.
Frequently asked questions
Why does menstrual cycle phase matter so much?
Circulating lymphocyte subsets, natural killer cell cytotoxicity and monocyte activation vary across the cycle with the hormonal environment, and the disease process is itself cyclical. Phase differences between arms can generate a difference that is hormonal rather than disease related.
Can cycle phase be determined after collection?
Not from the cell product alone. It must be recorded at the draw. Where donor-matched plasma or serum is supplied, circulating hormone levels can be measured to corroborate the recorded phase.
Should donors on hormonal therapy be excluded?
Usually not, since hormonal suppression is standard management and excluding it would leave an unrepresentative cohort. Record the therapy class and treat each as a distinct stratum, because gonadotropin releasing hormone therapy, combined contraceptives and progestins produce different hormonal states.
Is time since diagnosis a good measure of disease duration?
No. The interval between symptom onset and diagnosis is characteristically long, so two donors diagnosed in the same year may have had disease for very different periods. Capture symptom onset as well, while noting that it is recalled rather than documented.
Does surgical stage predict symptom severity?
Poorly. Staging describes lesion extent and adhesion burden and correlates weakly with pain. Decide deliberately whether the cohort axis is stage or symptom burden, because they select different populations.
Is there a defining autoantibody for endometriosis?
No. It sits in the inflammatory rather than the autoimmune part of the catalogue, with described features including altered peritoneal macrophage behavior and reduced natural killer cytotoxicity. A study designed around finding a disease-defining serological marker should be reconsidered.
What viability specification applies to this material?
Disease-state donor material carries a post-thaw viability specification above 80 percent. That figure applies to the disease-state line specifically and is not carried across from healthy donor products.
Can this material be used for clinical manufacturing?
No. Disease-state donor material is supplied for research use covering discovery, drug screening and biomarker work. Material intended for further manufacturing is a separate cGMP scope with its own agreement and documentation requirements.
Talk to OrganaBio
Sourcing an endometriosis cohort?
Donor selection can be scoped by disease state, HLA genotype and donor characteristics, subject to availability, and donor-matched plasma, serum and PBMCs are available from the same donor. Tell us the parameters your protocol needs and the scientific team will confirm what can be supplied.
