Immune Memory Remodels in Sex-Specific Waves From Birth to Old Age, Landmark Study Finds

The human immune system does not age in a straight line. Instead, it appears to rewrite itself in distinct, rhythmic waves — and the timing of those waves depends heavily on whether the body belongs to a man or a woman. That is the central conclusion of a sweeping new study published in Frontiers in Aging, in which a Brazilian research team profiled the memory T- and B-cell compartments of 1,796 healthy volunteers, from infants just nine months old to adults of 65 years, and mapped how the cellular architecture of adaptive immunity changes across the entire human lifespan.

The research, led by Joaquim Pedro Brito-de-Sousa and senior authors Ana Carolina Campi-Azevedo, Karen Cecília de Lima Torres, and Olindo Assis Martins-Filho, draws on samples collected between 2011 and 2019 at primary care vaccination centers in southeastern and northeastern Brazil. Volunteers were recruited when they presented for routine vaccination, and the team excluded anyone recently vaccinated, pregnant, HIV-positive, living with chronic immune-mediated disease, or taking immunosuppressive therapy. The cohort — 926 women and 870 men — was divided into twelve consecutive age bands, from under one year of age through 50 to 65 years, allowing the investigators to track immune remodeling with unusual granularity across childhood, adolescence, adulthood, and the threshold of old age.

At the heart of the study is a technical tour de force in flow cytometry. Peripheral blood mononuclear cells were isolated by density-gradient centrifugation and cultured for 144 hours before being stained with monoclonal antibodies against CD3, CD4, CD8, CD45RO, CD27, and the chemokine receptor CXCR3 (CD183) for T-cells, and against CD19, CD27, and IgD for B-cells. This combination allowed the researchers to resolve eight distinct T-cell phenotypes — including naïve, early effector, central memory, effector memory, and both interferon-mediated and non-interferon-mediated memory compartments — alongside four B-cell subsets spanning naïve, double-negative, unswitched memory, and class-switched memory cells. At least 100,000 lymphocytes were acquired per sample on an LSRFortessa cytometer, and the long culture period was deliberately chosen to let cells recover from isolation stress and resume homeostatic behavior before phenotyping.

The results reveal that immune memory remodeling is anything but gradual. Statistically significant shifts between adjacent age groups clustered into three discrete windows: an early transition around 5 to 6 years, a pronounced and prolonged wave between 10 and 19 years — the most dramatic of the entire lifespan — and a more subdued recalibration between 20 and 29 years. During the adolescent wave, memory and interferon-mediated memory T-cell subsets expanded sharply while naïve subsets contracted, and the B-cell compartment followed suit, with double-negative and unswitched memory cells rising as naïve CD19+ cells fell. Beyond the late twenties, the pace of change slowed markedly, with only scattered subset shifts in the fourth, fifth, and sixth decades of life.

Sex emerged as a defining variable. Women showed an earlier onset of change: declines in naïve and early activated subsets began as early as one year of age in females, whereas comparable shifts in males did not appear until the 10-to-19-year window. Men, however, exhibited greater lifelong variability in differentiated subsets — most strikingly in early effector CD4+ cells — with elevated median values for central memory, effector memory, and interferon-mediated CD4+ and CD8+ populations concentrated between 10 and 39 years. Signature analyses, which converted continuous cell frequencies into proportions of individuals above global median cut-offs, confirmed that the two sexes reached their peaks of high-producer status at distinct ages, with the 10-to-19-year range serving as the pivotal turning point for the population as a whole.

Logistic regression modeling reinforced the picture of directional, lifelong drift. Naïve T- and B-cell subsets — NCD4, NCD4, NCD8, NCD8, and NCD19 — showed continuously decreasing predicted probabilities with age, while virtually every memory subset, from central and effector memory CD4+ and CD8+ T-cells through unswitched and class-switched memory B-cells, climbed steadily from birth onward. Notably, an increase in early effector CD4+ cells and a decrease in early activated CD4+ cells were observed selectively in males, underscoring that the male trajectory is defined less by earlier onset than by greater amplitude of differentiation and inflammatory polarization.

Perhaps the most striking findings came from the network analyses. Using Spearman correlations among all memory subsets, the team built integrative connectivity maps for each age band and sex. Naïve cells displayed the highest overall connectivity, anchoring the immune network’s architecture. Total connections followed a wave-like pattern, with a peak at two years, a long-lasting plateau from 5 to 19 years, and a continuous decline thereafter. But the sexes diverged dramatically: in women, B-cell network connectivity increased with age and correlation density remained relatively stable throughout life, whereas in men, connectivity collapsed sharply after age 20. Correlation axes — shared connections between adjacent age ranges — emerged earlier in men, concentrated between 2 and 19 years, but persisted longer and more intensely in women, spanning 5 to 49 years. Importantly, the upregulation of memory cell subsets was accompanied by an increase in global connectivity, suggesting that phenotypic diversification and network integration are tightly coupled processes.

The authors frame these patterns within the concept of immunobiography — the idea, introduced by Franceschi and colleagues, that the immune system carries a lifelong record of antigenic encounters, endocrine transitions, and environmental exposures, inscribed in waves rather than accumulated uniformly. The CD27/CD45RO axis in T-cells and the CD27/IgD axis in B-cells serve as molecular ledgers of this history: CD27+CD45RO− cells mark the naïve compartment sustained by thymic output, while progressive transitions toward central and effector memory reflect mounting antigenic experience. The addition of CXCR3 further refines the picture, separating Th1/Tc1-polarized inflammatory memory cells shaped by viral and intracellular pathogens from non-Th1 trajectories associated with barrier immunity and B-cell help. The team also notes that their cohort, drawn from a region hyperendemic for parasitic and infectious diseases, may exhibit accelerated immunological remodeling relative to chronological age — a phenomenon their earlier work has linked to epigenetic aging and compensatory innate immune mechanisms in uninfected residents.

The study is not without limitations, which the authors acknowledge candidly. The observational design, non-probabilistic convenience sampling, and unequal sample sizes across age groups — particularly the small male cohorts in the 20-to-29 and 50-to-65-year ranges — constrain generalizability. The analysis was not adjusted for lifetime infectious exposure, cumulative vaccination, nutritional status, or endocrine transitions, though the authors argue that within the immunobiographical framework these factors are not mere confounders but intrinsic components of the biological record. No soluble immune mediators were measured alongside the cellular phenotyping, leaving the inflammatory dimension of the remodeling to be inferred rather than directly quantified.

Even so, the implications are considerable. The identification of discrete, sex-dependent remodeling windows — with early life and puberty emerging as critical periods — suggests that the foundation of immune resilience, and the susceptibility to chronic inflammatory disease in later life, may be set decades before old age arrives. The divergent network strategies adopted by male and female immune systems, with men losing connectivity as women sustain it, offer a mechanistic thread connecting cellular phenotype to lifelong inflammatory tone. As the authors conclude, the balance between central and late effector memory in both T- and B-cell compartments may prove to be a key determinant of immune flexibility versus inflammatory burden — a ledger written in childhood, balanced in adolescence, and cashed out across the decades that follow.

Subject of Research: Age- and sex-dependent remodeling of memory T- and B-cell immunophenotypes across the human lifespan

Article Title: Comprehensive profiling of phenotypic features of memory T- and B-cells from birth to the onset of old age

Article References: Brito-de-Sousa, J. P., Reis, L. R., Costa-Rocha, I. A. D., Peruhype-Magalhães, V., Costa-Pereira, C., Martins, J. P., Antonelli, L. R. D. V., Garcia, C. C., Gomes, A. O., Coelho-dos-Reis, J. G. A., Faria, A. M. D. C., Teixeira-Carvalho, A., Campi-Azevedo, A. C., Torres, K. C. D. L., & Martins-Filho, O. A. (2026). Comprehensive profiling of phenotypic features of memory T- and B-cells from birth to the onset of old age. Frontiers in Aging, 7, Article 1890974. https://doi.org/10.3389/fragi.2026.1890974

Image Credits: AI Generated

DOI: 10.3389/fragi.2026.1890974

Keywords: immunobiography, memory T-cells, memory B-cells, immunosenescence, flow cytometry, inflammaging, adaptive immunity, sex differences, immune network connectivity, naive T-cells, CXCR3, aging