Lung cancer remains one of the most formidable challenges in modern oncology, and non-small cell lung cancer (NSCLC) accounts for roughly 85 percent of all cases worldwide. While immunotherapy has transformed treatment for many patients, the immune system’s role in driving or restraining tumor growth is still only partially understood. A new prospective case-control study from Egypt, published in BMC Cancer, adds a striking piece to that puzzle: it reports that two populations of immune cells whose normal job is to calm inflammation — regulatory B cells (Bregs) and regulatory T cells (Tregs) — are found at significantly elevated levels in the blood of NSCLC patients, and that their abundance climbs in step with the severity of the disease.
The research team, led by investigators at Sohag and Assiut Universities, enrolled 40 patients with confirmed NSCLC and 40 age- and sex-matched healthy controls between January and December 2021. Patients underwent comprehensive staging, including chest and abdominal CT imaging, brain MRI or CT, bone scintigraphy, and fiber-optic bronchoscopy with biopsy. Disease extent was classified using the American Joint Committee on Cancer’s eighth-edition TNM system: five patients had stage II disease, fifteen had stage III, and twenty had stage IV, with regional lymph node metastasis present in twenty individuals. Histopathology revealed nineteen adenocarcinomas, fourteen squamous cell carcinomas, four undifferentiated carcinomas, and three large cell carcinomas.
Using multicolor flow cytometry, the researchers quantified circulating lymphocyte subsets with considerable technical precision. Tregs were identified as CD4-positive T cells co-expressing high levels of CD25 and the master transcription factor Foxp3, a combination that marks the most suppressive regulatory population. Bregs were defined as CD19-positive B cells expressing high levels of both CD24 and CD38 — the so-called immature or transitional B cell phenotype, which is known to secrete copious amounts of the anti-inflammatory cytokine interleukin-10. Fluorescence-activated cell sorting with isotype controls and mean fluorescence intensity measurements allowed the team to distinguish these rare regulatory populations from conventional lymphocytes with confidence.
The results were unambiguous. Compared with healthy controls, NSCLC patients showed significantly higher frequencies of CD8-positive cytotoxic T cells, CD4-positive CD25-high T cells, Foxp3-expressing Tregs, and Bregs, along with a significantly reduced CD4-to-CD8 ratio — a signature often interpreted as chronic immune perturbation. Notably, total CD19-positive B cell numbers did not differ between groups, suggesting that the expansion was specific to the regulatory subset rather than a general B cell proliferation. The differences for Bregs and Tregs were statistically robust, with Breg elevation reaching a p-value of 0.0001.
Perhaps the most clinically provocative finding emerged when the researchers stratified patients by disease status. Those with distant metastases carried significantly higher frequencies of both Bregs and Tregs than patients whose disease had not spread beyond the chest. Both cell populations also rose significantly across TNM stages, with stage IV patients showing the highest levels, and both were significantly associated with histopathological subtype, peaking in adenocarcinoma. Intriguingly, the frequencies of the two regulatory populations correlated positively with each other, hinting at a coordinated regulatory axis rather than two independent phenomena.
That coordination makes biological sense. Prior work has shown that Bregs can promote the expansion and suppressive function of Tregs through direct cell-to-cell contact and through secretion of interleukin-10 and interleukin-35, upregulating Foxp3 and CTLA-4 in T cells. In the tumor microenvironment, Foxp3-positive Tregs can suppress cytotoxic T lymphocytes by interfering with the release of cytolytic granules, effectively disarming the body’s main tumor-killing weapon. The study’s authors argue that the elevated circulating Bregs and Tregs they observed likely mirror the same immunosuppressive axis documented inside tumors, and that blood-based measurement offers a non-invasive window into processes previously accessible only through tissue biopsy.
The cytokine data reinforce that interpretation. Using a multiplex Luminex assay, the team measured seven serum cytokines — interleukin-1 beta, interleukin-6, interleukin-17, tumor necrosis factor-alpha, interleukin-10, interleukin-35, and transforming growth factor-beta 1 — and found every one of them significantly elevated in patients compared with controls. Moreover, patients with distant metastases had significantly higher levels of all of these except interleukin-1 beta, and several cytokines, including interleukin-6, interleukin-17, tumor necrosis factor-alpha, interleukin-10, and TGF-beta 1, differed significantly across TNM stages. The pattern suggests a tumor-promoting inflammatory milieu in which pro-inflammatory and anti-inflammatory signals rise together, a paradoxical combination well described in cancer-related inflammation.
Each of these soluble mediators carries mechanistic weight. Interleukin-6 overexpression has repeatedly been linked to advanced stage and metastasis in lung cancer. Interleukin-17, produced by Th17 cells, exerts complex effects on tumor growth and spread. Interleukin-35, a relative newcomer to the interleukin-12 family, has been shown to drive CD8-positive T cell dysfunction and exhaustion, blunting antitumor immunity. TGF-beta 1 is among the most potent inducers of epithelial-mesenchymal transition in NSCLC cells, fueling invasion and metastatic potential, and several of these cytokines intersect with VEGF-mediated angiogenesis and vascular remodeling that support tumor expansion and immune exclusion.
The statistical picture is nuanced. In univariate logistic regression, higher Breg frequencies were inversely associated with lymph node involvement, and higher CD8 counts were linked to lower tumor grade, while an elevated CD4-to-CD8 ratio was positively associated with advanced grade. Yet when the researchers adjusted for multiple predictors simultaneously, none of the immune variables retained statistical significance — a result the authors attribute candidly to the modest sample size of forty patients, which limits statistical power. They emphasize that the consistent directionality of the effect estimates across models remains biologically plausible and aligned with established immunosuppressive mechanisms in NSCLC, and they call for validation in larger prospective cohorts.
The study has other acknowledged limitations. It included no stage I patients, reflecting a local reality in which most lung cancer cases in the region present at advanced stages, and its observational design establishes association rather than causation. Even so, the work’s central strength is compelling: a simple, non-invasive blood test that captures both the cellular and soluble arms of immune regulation and tracks them against disease stage and metastasis. If confirmed at scale, circulating Bregs, Tregs, and their cytokine signatures could become accessible surrogate biomarkers for the immunosuppressive tumor microenvironment — tools for monitoring disease progression, guiding immunotherapy decisions, and identifying patients whose regulatory immune networks are quietly helping their tumors hide.
Subject of Research: Association of circulating regulatory B cells, regulatory T cells, and serum cytokines with disease stage in non-small cell lung cancer
Article Title: Association of regulatory B, T cells and cytokine production with disease stage in non-small cell lung cancer patients: prospective case control study
Article References: Association of regulatory B, T cells and cytokine production with disease stage in non-small cell lung cancer patients: prospective case control study. (n.d.). https://doi.org/10.1186/s12885-026-16464-7
Image Credits: AI Generated
DOI: 10.1186/s12885-026-16464-7
Keywords: non-small cell lung cancer, regulatory B cells, regulatory T cells, cytokines, flow cytometry, tumor immunology, metastasis, interleukin-10, interleukin-35, TGF-beta, biomarkers, immunosuppression
News Source: Nathaniel Bowman. (October 14, 2026). Regulatory Immune Cells Rise With Lung Cancer Severity, Blood Study Finds. Scienmag.
