FISH IMMUNE CELL MARKERS

Cells can be identified using their protein expression profiles

It is well established from studies in mammals that different types of cells carry distinct arrays of proteins on their cell surface or within their cytoplasm. Thus, not only can cells be distinguished based on their morphology (i.e. how they look under a microscope), they can also be distinguished depending on which combinations of extracellular or intracellular proteins that they express. Furthermore, the differentiation/activation state of a cell can be determined by looking at which proteins are expressed and at which level each individual protein is expressed. For example, consider the T- and B-lymphocytes. Every T-and B-cell has about 100,000 molecules on its surface. B cells have CD21, CD35, CD40, and CD45 in addition to other molecules on their surfaces whereas T-cells have CD2, CD3, CD4, CD28, CD45R, and other molecules on their surfaces. T-cells can be further divided into cytotoxic T-cells or helper T-cells that express either CD8 proteins or CD4 proteins on their surfaces respectively. When taking a look at, say, CD8+ T-cells at their different states of differentiation, the molecular profile changes from naïve cells to activated (effector) cells to memory cells (see the table below). Thus, recognizing a cell’s molecular profile is very important for understanding what cell-type it is and how that cell should be behaving.

Molecular profile for CD8+ T-cells – molecules expressed and their relative levels

	CD8	CD127	CD62L	CD45	CCR7	IL-2	IFN-g
Naïve	+	High	High	RA	High	Low	Low
Effector	+	Low	Low	RO	Low	Low	High
Effector memory	+		Low	variable	Low
Central memory	+		High	variable	High

Discovering the protein expression profiles of fish cells

Despite the large amount of information that exists to study human and mouse cells, the information and cellular reagents needed to study the cells of many other vertebrate species are sparse. Many researchers are attempting to fill the gaps in the knowledge for these other species by using a comparative approach to first identify the orthologous genes to the known human/mouse cell surface (or intracellular) molecules, and then to develop recombinant proteins and antibodies against those proteins that can be then used for cellular analyses. In addition to the many great laboratories worldwide addressing this shortfall, a consortium of scientists working together with the U.S. Veterinary Immune Reagent Network is performing a major effort with regard to identifying and analyzing molecules of the immune system in domesticated animals with an emphasis on helping with disease control. What this website aims to do is collate information concerning important molecules associated with immune cells of teleost fish hopefully making life a little easier for the scientists working in this extremely important field. Although much of the information is still in the early stages (as is this website!), I’m sure that rapid progress is sure to follow, so watch this site for regular updates!

Important immune cell-surface molecules of bony fish

CD8 molecules – mammalian expression = thymocyte subsets and MHC class I restricted T-cells

Species	Marker name	Sequence type	Genbank accession #	Published article	TIGR gene index
Atlantic salmon Salmo salar	CD8 beta	mRNA	AY693394	15829311	Atlantic salmon
Atlantic salmon Salmo salar	CD8 alpha	mRNA	AY693393	15829311	Atlantic salmon
Atlantic salmon Salmo salar	CD8 beta	genomic	AY693392	15829311	Atlantic salmon
Atlantic salmon Salmo salar	CD8 alpha	genomic	AY693391	15829311	Atlantic salmon
Atlantic salmon Salmo salar	CD8 beta splice variant	mRNA	AY701522	15829311	Atlantic salmon
Atlantic salmon Salmo salar	CD8 alpha splice variant	mRNA	AY701521	15829311	Atlantic salmon
Brown trout Salmo trutta	CD8 beta	mRNA	AY701524	15829311
Brown trout Salmo trutta	CD8 alpha	mRNA	AY701523	15829311
European sea bass Dicentrarchus labrax	CD8 alpha	mRNA	AJ846849	16230027
European sea bass Dicentrarchus labrax	CD8 alpha	mRNA	DQ090838	16414122
Gilthead seabream Sparus aurata	CD8 alpha	mRNA	AJ878605	Aquaculture Volume 256, Issues 1-4 2006, Pages 631-637
Japanese flounder Paralichthys olivaceus	CD8 alpha	mRNA	AB082957 C82240	10689095
Rainbow trout Oncorhynchus mykiss	CD8 beta	mRNA	AY563420	15829311	Rainbow trout
Rainbow trout Oncorhynchus mykiss (OSU-142 strain)	CD8 alpha Onmy-CD8A.1 allele	Genomic	AF178055	10706703	Rainbow trout
Rainbow trout Oncorhynchus mykiss (ARO-F2 strain)	CD8 alpha Onmy-CD8a.2 allele	mRNA	AF178054	10706703	Rainbow trout
Rainbow trout Oncorhynchus mykiss (OSU-142 strain)	CD8 alpha	mRNA	AF178053	10706703	Rainbow trout
Zebrafish Danio rerio	CD8 alpha	mRNA	AB186400	15854681	Zebrafish

CD4 molecules– mammalian expression = thymocyte subsets, MHC class II restricted T cells, monocytes and macrophages

Species	Marker name	Sequence type	Genbank accession #	Published article	TIGR gene index
Channel catfish Ictalurus punctatus	CD4-like protein 2	mRNA	DQ435302	doi:10.1016/j.dci.2006.05.012	Channel catfish
Channel catfish Ictalurus punctatus	CD4-like protein 1	mRNA	DQ435301	doi:10.1016/j.dci.2006.05.012	Channel catfish
Rainbow trout Oncorhynchus mykiss	CD4L-2b*01 allele	mRNA	AY899932	16337483	Rainbow trout
Rainbow trout Oncorhynchus mykiss	CD4L-2a*02 allele	mRNA	AY899931	16337483