Determination of reference values: numbers, repertoire and products of leukocytes in immunological healthy elderly

Peripheral blood leukocytes consist of different types of cells, namely
monocytes, granulocytes, B-lymphocytes and T-lymphocytes. The B and T
lymphocytes can be further differentiated into various subtypes, based on
protein markers on the cells, which differ in function and/or activation
status. At the membrane of B and T lymphocytes molecules are present that can
specifically recognize antigens. These are called resp. immunoglobulin (IG) and
T cell receptor (TR) molecules. Each B or T lymphocyte basically has a unique
IG or TR molecule.

All IG and TR molecules together provide a broad, so-called polyclonal,
repertoire of antigen-specific receptors. It is known that infections,
especially viral infections, can cause changes in numbers of B and T
lymphocytes (subtypes) and in the IG/TR repertoire. It is also clear from
literature that the relative distribution of the various subtypes of B and T
lymphocytes can differ depending on age. It is also known that in older
individuals (defined as >65 years) a narrowing of the repertoire can occur,
whereby even clones of B or T lymphocytes can be detected. However, for
example, reference values **for the current, improved and more informative
phenotyping protocols for B and T lymphocytes and their subtypes and for their
products (antibodies, cytokines) are lacking. There is also insufficient
detailed insight into the age-dependent changes in the IG / TR repertoire.

Such testing of reference values in elderly, healthy individuals is essential
for two reasons:
1. insight into the age-dependent distribution of (subtypes of) leukocytes,
their IG / TR repertoire and their production of antibodies and cytokines;
2. use for correct (and age-dependent) interpretation of deviating values **in
certain patient groups (such as patients with chronic lymphocytic leukemia,
autoimmune diseases, etc.).

Generation of (age-dependent) reference values **of leukocytes and their
subtypes and of their products, as well as analysis of (age-dependent) IG / TR
repertoire. In order to be able to distinguish the age-dependent effects from
effects caused by viral infections, it is important to know the specific immune
response of healthy persons to viral infections in particular.

Prospective, observational study

This study has a minimal burden on the participant and there are no risks
involved