Biology subjects

Borghans, J. A.

Publications and source records attributed to Borghans, J. A..

3 recordsLinked to original sources

bioRxiv2021

Age-dependent normalisation functions for T-lymphocytes in healthy individuals

Lymphocyte numbers naturally change through age. Normalisation functions to account for this are sparse, and mostly disregard measurements from children in which these changes are most prominent. In this study, we analyse cross-sectional numbers of mainly T-lymphocytes (CD3+, CD3+CD4+ and CD3+CD8+) and their subpopulations (naive and memory) from 673 healthy Dutch individuals ranging from infancy to adulthood (0-62 years). We fitted the data by a delayed exponential function and received parameter estimates for each lymphocyte subset. Our modelling approach follows general laboratory measurement procedures in which absolute cell counts of T-lymphocyte subsets are calculated from observed percentages within a reference population that is truly counted (typically the total lymphocyte count). Consequently, we receive one set of parameter estimates per T-cell subset representing both the trajectories of their counts and percentages. We allow for an initial time delay of half a year before the total lymphocyte counts per {micro}l of blood start to change exponentially, and we find that T-lymphocyte trajectories tend to increase during the first half a year of life. Thus, our study provides functions describing the general trajectories of T-lymphocyte counts and percentages of the Dutch population. These functions provide important references to study T-lymphocyte dynamics in disease, and allow one to quantify losses and gains in longitudinal data, such as the CD4+ T-cell decline in HIV-infected children, and/or the rate of T-cell recovery after the onset of treatment.

immunology↗

bioRxiv2021

Turnover of MCMV-expanded CD8+ T-cells is similar to that of memory phenotype T-cells and independent of the magnitude of the response

The potential of memory T-cells to provide protection against re-infection is beyond question. Yet, it remains debated whether long-term T-cell memory is due to long-lived memory cells. There is ample evidence that blood-derived memory phenotype CD8+ T-cells maintain themselves through cell division, rather than through longevity of individual cells. It has recently been proposed, however, that there may be heterogeneity in the lifespans of memory T-cells, depending on factors such as exposure to cognate antigen. Cytomegalovirus (CMV) infection induces not only conventional, contracting T-cell responses, but also inflationary CD8+ T-cell responses, which are maintained at unusually high numbers, and are even thought to continue to expand over time. It has been proposed that such inflating T-cell responses result from the accumulation of relatively long-lived CMV-specific memory CD8+ T-cells. Using in vivo deuterium labelling and mathematical modelling, we found that the average production rates and expected lifespans of mouse CMV-specific CD8+ T-cells are very similar to those of bulk memory-phenotype CD8+ T-cells. Even CMV-specific inflationary CD8+ T-cell responses that differ three-fold in size, were found to turn over at similar rates.

immunology↗

bioRxiv2018

Off-target effects of Cre recombinase reveal limits of adoptive T cell transfers and persistent proliferation of effector CD8 T-cells

Effector-memory T-cells (TEM) are assumed to be short-lived cells that poorly proliferate upon antigenic restimulation, thus depending on central-memory T-cells (TCM) to replenish their numbers during homeostasis, largely depending on adoptive transfer evidence. Here we analyzed T cells in their natural environment and observed robust long-term in vivo cycling within the TEM subset that was stronger than the one in the TCM subset. Murine Cytomegalovirus (MCMV) induces inflationary TEM responses that remain high during latency. We analyzed Ki67 expression during acute and latent MCMV infection and found Ki67hiBcl2lo TEM in latently infected mice, arguing for antigen-driven TEM proliferation. TEM acquired deuterium more rapidly than TCM in an in vivo labeling experiment, and were replenished more rapidly than TCM after memory depletion, suggesting that TEM cycle faster than TCM. We depleted selectively the proliferating T-cells by Cre-overinduction, which resulted in a selective loss of Ki67hiBCl2lo effector T-cells, and an increase in the death of TEM in the spleen, while it hardly affected the TCM subset, arguing for robust proliferation of TEM in the spleen. On the other hand, TEM homing to the spleen upon adoptive transfer was substantially poorer than TCM, explaining the previously reported expansions of TCM, but not TEM, upon transfer. In conclusion, our data suggest that memory inflation is maintained by proliferation of antigen-specific TEM, rather than by continued expansion and differentiation of TCM.\n\nAuthor SummaryThe naive T cell population consists of T cells that have the potential to recognize millions of different pathogens. Upon infection, naive T cells that recognize the pathogen expand, and differentiate into effector T cells that eliminate infected cells. Once the infection is contained, the T cell pool contracts and only a small population of central memory T cells remains that can expand quickly upon re-infection. Cytomegaloviruses cause persistent infections that are not cleared from the organism after the initial immune response. In infected individuals a pool of CMV-specific effector memory T cells dominates the immune system in a phenomenon called memory inflation. Previous research using the transfer of central memory or effector memory T cells from CMV-infected mice into mice with a matching infection, showed expansion of central memory T cells but not effector memory T cells. Here we show that effector memory T cells have a reduced capacity to home into lymphoid organs, where T cell activation takes place, compared to central memory T cells. Using methods that do not interfere with T cell differentiation and homing, we show that effector memory T cells are proliferating during the persistent phase of CMV infection, significantly contributing to the upkeep of the inflationary population.

immunology↗