Recently I have been working with detecting serum IL12 by ELISA. Based on that result, the sera from healthy mice have around 10000~20000pg/mL IL12p40/p70. But when I searched the literature, IL-12p40 is around 200pg/mL. The coating antibody and detection antibody I used can both recognize p40 and p70. The standard curve looked fine. I diluted the serum by 30 fold, and I could still detect the OD signal. And the negative control (buffer alone) had a low background.
I am wondering whether it is because the antibody can detect both p40 and p70. Still, the concentration of p40 plus p70 is too high. And does anybody know what specific antibody should I use to only detect IL12?