"Mechanisms and clinical significance of cell volume regulation
Background

The ability to avoid excessive changes of cell volume is one of the
most obvious requirements for cell survival. For cell volume constancy
osmotic gradients across the cell membrane must remain small despite
everchanging intracellular and extracellular concentrations of
osmotically active substances. Any osmotic gradient across human and
animal cell membranes is followed by respective movements of water,
since most cell membranes are highly permeable to water and not rigid
enough to build up significant transmembrane hydrostatic pressure
gradients. Obviously, excessive cell swelling will eventually lead to
disruption of the fragile cell membranes and thus to cell death. Beyond

that and probably even more important, cell volume alterations
compromize constancy of intracellular milieuand cell function by
changing concentrations of all cellular components including
macromolecules (macromolecular crowding). Volume regulatory mechanisms
serve to dissipate the osmotic gradient and thus to prevent or reverse
changes of cell volume. They include ion and organic osmolyte transport

across the cell membrane, cellular formation of organic osmolytes and
altered metabolism of macromolecules. The large number of cell volume
regulatory mechanisms is matched by a similar diversity of
intracellular signals creating a rapid, highly powerful and sensitive
machinery which is is turned on by only a few percent of cell swelling
or cell shrinkage. alterations of extracellular ion composition and
concentration, energy depletion, metabolism and transport across the
cell membrane. Cell volume regulatory mechanisms participate in the
regulation of diverse cellular functions such as epithelial transport,
metabolism, excitability, phagocytosis, migration, cell proliferation,
necrotic and apoptotic cell death.
http://www.physiologie.medizin.uni-tuebingen.de/DepI/HeadInfos/Resear...

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Hello,

The above quote tells us how cell size can matter. MCV is measured with

CBC test which is related to average volume of a red blood cell.
However, average volume of a white blood cells is not measured but
their numbers are only measured. In case of hypertonicity or
hypotonicity of body fluids and ICF, cell size can change and can be
responsible for many functions and disorders.

Can you tell me that whether size of WBCs can also be effected by
different tonicities of fluids?

Can inter-movement of water in ICF and ECF be effected by any change in

cell membranes of RBCs and WBCs due to any disorder? I.E. cells remain
in their changed sizes (swelled or shrinked) more than the normal cells

due to change in membrane's normal potencial/capacity to hold water.

Cells (WBCs?) may brust due to excess water intracellularily as
cytolysis. Can  particles of cells on their cytolysis act as antigens
to immune cells?

Best wishes.