VOL. 4, No. 1, January 2008

W. Allaerts [2008] Med. Hypotheses Res. 5: 37‒51.

Towards the Development of Annotation Grids for Cell
Lineage Studies: I. Study of Paradigm Shifts

Wilfried Allaerts*

Biological Publishing, PO Box 104, NL-7440 AC Nijverdal, The Netherlands

Abstract. The definition of cell groups and cell systems has been the subject of many
controversies. In the present study, five cell biological frameworks are investigated, namely
the reticulo-endothelial system (RES), the mononuclear phagocyte system (MPS), the group
of dendritic cells (DC) and interdigitating reticulum cells (IDC), the follicular dendritic cells
(FDC) and the folliculo-stellate cell (FSC) system of the anterior pituitary. The contrasts and
overlap between the different cell groups and systems are used to analyse the paradigm shifts
in current cell lineage studies. For instance, the intensity and frequency of phagocytic activity
was declared a group defining characteristic of the RES. For the MPS, linkage to a common
precursor cell in the bone marrow was mandatory and also a ground for exclusion from the
system. Progenitor-progeny relations, however, have not been traceable in all cell systems
reported. In the FSC system, the observation of a partial overlap with cells belonging to the
MPS, and the presence of features reminiscent of progenitor cells, has urged for a new
framework to outline this cell group. Historical contingencies affect the successive alterations
of cell biological concepts resulting in a number of paradigm shifts in cell biological
research. The introduction of high throughput technology has profoundly influenced the
methods for cell identification and classification, especially in cancer immunology. The
homogeneity of tumor cell populations, however, forms an important condition affecting the
outcome of microarray analysis, like for instance in leukemia. On the other hand, linkage of
genes from adjacent locations in (chromosome) regions of increased gene expression, has
been reported to affect differentiation mechanisms. Challenges from microarray studies
therefore are instrumental for establishing the essential parameters for an annotation grid for
cell lineage studies.

* Correspondence: Dr. Wilfried Allaerts, Biological Publishing, PO Box 104, NL-7440
AC Nijverdal, The Netherlands.

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