Quantification of Immunological Memory

The immune system helps us to deal with infectious diseases by clearing infection and, more importantly, by mediating immunity for subsequent reinfections. Thanks to vaccines, we can educate the immune system and obtain immunity even without a primary infection. A major issue in the development of vaccines, however, is that we have limited tools for assessing the achievement of immunity, without relying on long term observation.
Serological memory, namely the long-term persistence of specific antibody titers, and immunological memory, meaning the ability for a secondary immune response increased in speed and magnitude, are the known correlates of immunity. Antibody titers are comparatively easy to measure, however, their long-term persistence cannot be currently inferred from short term observations. Immunological memory is more complex to assess; it is a system-level property of the immune system, that arises from an increase in the frequency of antigen-specific B and T lymphocytes as well as from the differentiation of antigen-experienced lymphocytes into qualitatively different cell populations, namely memory cells. Thus, the quantification of immunological memory requires both accurate measures to identify all the relevant cell types and the ability to model the dynamics of the immune response, so as to predict its long term fate.

Immunological memory is programmed in a comparatively early time window and established in multiple stages, in the first few weeks after exposure to antigen, and potentially even in the first few days of an immune response. The magnitude and duration of immunological memory are known to greatly differ among individuals and across different pathogens, antigens, and immunization protocols. Interindividual differences in immunological memory can be observed even in inbred mice undergoing the same immunization procedure.
There are still open questions on the quantification of immunological memory. For instance, whether is it possible to quantify it early on while the immune response develops and what are the most relevant molecules or cell populations that can support this assessment.
We propose here a Research Topic focused on the quantification of immunological memory. We aim to collect contributions on the definitions of immunological memory, and on molecules, mechanisms, and cell subsets involved in this phenomenon. Contributions presenting methods and models, both in vivo and in silico, to quantify immunological memory are also particularly encouraged.

We welcome the submission of Original Research, Review, Mini Review, Methods, Case Reports, and Clinical Trial articles related to, but not limited to, the following topics:

• T cell and B cell memory subtypes and their transcriptional patterns, cytokine production, and cell to cell interactions
• Time scales of immunological memory development and duration
• Analysis of immunological memory with a systems biology approach
• Single-cell data analysis in immunological memory
• TCR and BCR clonal diversity in immunological memory
• Quantification of immunological memory, in humans or animal models, after infection or vaccination
• Early correlates of memory: predictors of enhanced response to a subsequent antigen re-encounter
• The contribution of immunological memory to individual immunity and to herd immunity
• Quantitative modeling of immunological memory in silico
• Analysis of immunological memory in mathematical/computational models of the immune response