The non-adherent cells were removed by vigorous pipetting, and the suspended cells were collected by centrifugation at 350g for 10 min. The cells remaining in the wells were regarded as adhered Protein Tyrosine Kinase inhibitor cells. To investigate differential expression of the CD2f isoforms in different lymphocyte subsets, we separated the lymphocyte subsets using anti-CD8α, CD4, and IgM monoclonal antibody (mAb) [34] and [35]. Kidney cells from the S3n strain of ginbuna crucian carp were dispersed by pressing

the tissues through a 150-gauge mesh stainless steel sieve in OPTI-MEM. The cells were washed with OPTI-MEM before layering onto a Percoll density gradient of 1.08 g/ml, and centrifuged at 350g for 20 min at 4 °C. Cell layers on the Percoll were collected and washed three times with OPTI-MEM. The cell suspension was incubated with a 1:104 dilution of rat anti-ginbuna CD8α mAb (mouse ascites) on ice. The cells were then washed twice with OPTI-MEM-10 and incubated on buy Stem Cell Compound Library ice for 20 min with 1 ml of a 1:5 dilution of magnetic bead-conjugated goat anti-rat Ig antibody (Miltenyi Biotec GmbH, Bergisch Glabach, Germany) and then re-washed a further thrice. Surface Ig (sIg)-positive and -negative cells were separated with a magnetic separation system (Mini Macs, Miltenyi Biotec) by applying the cell suspension to a plastic column equipped with an external magnet. The CD8α-positive cells were retained in the column, while the CD8α-negative

cells passed through. Both cell fractions were collected and viability was confirmed to be greater than 95% by the trypan blue dye exclusion method. Subsequently, negative cells were incubated with a 1:104 dilution

of rat anti-ginbuna CD4 mAb (mouse ascites) on ice. The protocol almost for purification of CD4-positive cells was essentially the same as that described for the CD8α-positive cells. In addition, IgM-positive cells were purified from different fish following a previously described protocol [25]. Total RNA was extracted from these purified leukocyte subpopulations using NucleoSpin RNA II (Machery-Nagel), according to the manufacturer’s protocol, and then reverse-transcribed with SuperScript II RNaseH-reverse transcriptase (Invitrogen) and oligo (dT) primer. RT-PCRs for amplification of caauCD2f were carried out with the following specific primer sets: CD2f-F9 and CD2f-1-R1 for caauCD2f-1; CD2f-F9 and CD2f-2-R2 for caauCD2f-2; CD2f-F10 and CD2f-3-R1 for caauCD2f-3; and CD2f-F9 and CD2f-4-R1 for caauCD2f-4 (see Table 1). AmpliTaq Gold DNA polymerase (Applied Biosystems) was used. The PCR conditions were as follows: 95 °C for 5 min and 36–40 cycles of 95 °C for 15 s, 65 °C for 30 s, and 72 °C for 10 min for amplification of the caauCD2fs; 95 °C for 5 min and 30 cycles of 95 °C for 15 s and 65 °C for 30 s plus 72 °C for 10 min for amplification of SAP; and 95 °C for 5 min and 36 cycles of 95 °C for 15 s, 65 °C for 30 s, and 72 °C for 10 min for amplification of CD8α.