Unit Conversion Table

A unit is defined according to the standard by which it is compared. For instance, the World Health Organization (WHO) offers protein reference standards that are accessible to everyone and allow for the normalization of activity definitions across proteins from different sources. These are available from NIBSC.

The activity of the protein reference standard is indicated by the number of units contained in a given mass of material. Typically, units are referred to as reference units (RU). When the reference material has been tested successfully in international, multi-center, collaborative studies it will be designated a WHO international standard, the units will then be International units (IU).

If there is a protein reference standard available, R&D Systems compares the activity of the reference standard with our protein, allowing for the conversion of mass into units (see table below).

Are all units the same?

No. One must be careful when comparing units of activity between sources. Different suppliers may have their own method for defining a unit. The method used, such as comparison with a WHO standard, must be the same between sources for a unit comparison to be valid. For this reason R&D Systems typically refers to proteins by their mass and activity by ED50.

Sample Conversion R&D Systems Recombinant Human BMP-2 to Equivalent Units

To calculate the approximate mass/concentration of an R&D Systems cytokine in units, multiply the mass/concentration (in µg) by the ‘R&D Systems Cytokine 1 µg = units’ column in the chart, the second column from the right. For instance, a 10 µg vial of rhBMP-2, catalog #355-BM, would contain 7,810 units (10 times 781).
R&D Systems Cytokine R&D Systems Catalog Number Reference Cytokine NIBSC Product Number Reference Standard Units/µg Cell Line used for Bioassay R&D Systems Cytokine 1 µg = units Unit Status
rhActivin A 338-AC rhActivin A 91/626 1 K562 1 IU
rhBDNF 248-BD rhBDNF 96/534 800 BaF/3 hTrkB 1.3 x 103 RU
rhBMP-2 355-BM rhBMP-2 93/574 500 ATDC-5 781 RU
rhEGF 236-EG rhEGF 91/530 1.0 x 103 Balb-3T3 1.4 x 103 IU
rhEpo 286-EP rhEpo 11/170 150 TF-1 150
(1 U = 1 WHO U)
IU
rhFGF-7 251-KG rhFGF-7 03/148 900 4MBr-5 520 RU
rhFGF basic 233-FB rhFGF basic 90/712 800 NR6R-3T3 800 IU
rhFSH 5925-FS rhFSH 92/642 13.8 HEK293/h FSH R 17.5 IU
rhFlt-3 Ligand 308-FK rhFlt-3 Ligand 96/532 1.0 x 103 Baflt 1.2 x 103 RU
rhG-CSF 214-CS rhG-CSF 88/502 1.0 x 105 NFS-60 2.6 x 105 IU
rhGH 1067-GH hGH 80/505 2.6 x 10-3 Nb2-11 5.4 x 10-3 IU
rhGM-CSF 215-GM rhGM-CSF 88/646 1.0 x 104 TF-1 1.5 x 104 IU
rmGM-CSF 415-ML rmGM-CSF 91/658 1.0 x 105 DA3 3.5 x 105 RU
rhGRO alpha 275-GR rhGRO alpha 92/722 1.0 x 105 PMN 2.11 x 105 RU
rhHGF 294-HG rhHGF 96/564 1.0 x 103 Saos-2 1.5 x 103 IU
rhIFN-beta 8499-IF rhIFN-beta 00/572 2.0 x 105 HeLa 2.8 x 105 IU
rhIFN-gamma 285-MI rhIFN-gamma 87/586 2.0 x 104 HeLa 2.0 x 104 IU
rmIFN-beta 8234-MB mIFN-beta NR-3079** NA L929 1.2 x 106 IU
rmIFN-gamma 485-MI rmIFN-gamma NIHGg02-901-533 1.0 x 103 L929 8.43 x 103 IU
rhIGF-I 291-G1 rhIGF-I 91/554 1 MCF-7 1.9 IU
rhIGF-II 292-G2 rhIGF-II 96/538 1000 MCF-7 850 IU
rhIL-1 alpha 200-LA rhIL-1 alpha 86/632 1.0 x 105 D10.G4.1 1.6 x 105 IU
rmIL-1 alpha 400-ML rmIL-1 alpha 93/672 1.0 x 106 D10.G4.1 7.1 x 105 RU
rhIL-1 beta 201-LB rhIL-1 beta 86/680 1.0 x 105 D10.G4.1 1.4 x 105 IU
rmIL-1 beta 401-ML rmIL-1 beta 93/668 1.0 x 106 D10.G4.1 1.1 x 106 RU
rhIL-1ra 280-RA rhIL-1ra 92/644 1.0 x 10-3 D10.G4.1 1.0 x 10-3 RU
rhIL-2 202-IL rhIL-2 86/500 1.4 x 104 CTLL-2 2.1 x 104 IU
rmIL-2 402-ML rmIL-2 93/566 1.0 x 105 CTLL-2 2.5 x 105 RU
rhIL-3 203-IL rhIL-3 91/510 1.7 x 103 TF-1 1.8 x 103 IU
rmIL-3 403-ML rmIL-3 91/662 1.0 x 105 NFS-6 1.7 x 105 RU
rhIL-4 204-IL rhIL-4 88/656 1.0 x 104 TF-1 2.9 x 104 IU
rmIL-4 404-ML rmIL-4 91/656 1.0 x 104 HT-2 1.8 x 105 RU
rhIL-5 205-IL rhIL-5 90/586 1.0 x 104 TF-1 4.4 x 104 RU
rhIL-6 206-IL rhIL-6 89/548 1.0 x 105 T1165.85.2.1 1.1 x 105 IU
rmIL-6 406-ML rmIL-6 93/730 1.0 x 105 T1165.85.2.1 9.0 x 105 RU
rhIL-7 207-IL rhIL-7 90/530 1.0 x 105 activated PBL 4.4 x 105 RU
rmIL-7 407-ML rmIL-7 93/740 5.0 x 104 activated PBL 1.5 x 105 RU
rhIL-8 208-IL rhIL-8 89/520 1.0 x 103 PMN see below* IU
rhIL-9 209-IL rhIL-9 91/678 1.0 x 104 MO7e 8.4 x 103 RU
rmIL-9 409-ML rmIL-9 93/504 NA TS1 0.9 µg NA
rhIL-10 217-IL rhIL-10 93/722 5.0 x 103 MC/9 1.45 x 104 RU
rhIL-11 218-IL rhIL-11 92/788 1.0 x 104 T11 1.05 x 104 IU
rhIL-12 219-IL rhIL-12 95/544 1.0 x 104 PBL 1.1x 104 RU
rhIL-13 213-ILB rhIL-13 94/622 1.0 x 103 TF-1 780 RU
rhIL-15 247-IL rhIL-15 95/554 1.0 x 104 MO7e 4.5 x 105 RU
rhLeptin 398-LP rhLeptin 97/594 800 BaF3/h OB R 1.2 x 103 IU
rmLeptin 498-OB rmLeptin 97/626 1.0 x 103 BaF3/h OB R 1.7 x 103 IU
rhLIF 7734-LF rhLIF 93/562 1 x 104 TF-1 1.27 x 104 RU
rhM-CSF 216-MC rhM-CSF 89/512 6.0 x 104 M-NFS-60 1.68 x 105 IU
rhMCP-1 279-MC rhMCP-1 92/794 1.0 x 103 MNC 1.36 x 103 RU
rhMCP-2 281-CP rhMCP-2 96/594 2.5 x 103 MNC see below* RU
rhMIP-1 alpha 270-LD rhMIP-1 alpha 92/518 100 MNC 200 RU
rhMIP-1 beta 271-BME rhMIP-1 beta 96/588 1.0 x 103 MNC 1.6 x 103 RU
rhbeta-NGF 256-GF rhbeta-NGF 93/556 1.0 x 103 TF-1 1.0 x 103 RU
rhNT-3 267-N3 rhNT-3 98/718 1.0 x 103 BaF/3 hTrkB 2.1 x 103 RU
rhOSM 295-OM rhOSM 93/564 5.0 x 104 TF-1 6.2 x 104 RU
rhPDGF-BB 220-BB rhPDGF-BB 94/728 750 NR6R-3T3 5.8 x 103 IU
rhProlactin 682-PL rhProlactin 84/500 0.0212 Nb2-11 0.054 IU
rhRANTES 278-RN rhRANTES 92/520 1.0 x 104 MNC 2.5 x 104 RU
rhSCF 255-SC rhSCF 91/682 1.0 x 103 TF-1 564 RU
porcine TGF-beta 1 101-B1 bTGF-beta 1 89/516 18750 HT-2 2.1 x 104 RU
porcine TGF-beta 2 102-B2 hTGF-beta 2 90/696 2.0 x 104 HT-2 5.6 x 104 RU
rhTGF-beta 240-B rhTGF-beta 1 89/514 1.9 x 104 HT-2 2.5 x 104 RU
rhTGF-beta 3 243-B3 rhTGF-beta 3 09/234 1.9 x 104 HT-2 2.2 x 104 IU
rhTNF-alpha 210-TA rhTNF-alpha 88/786 4.65 x 104 L-929 7.6 x 104 IU
rmTNF-alpha 410-MT rmTNF-alpha 88/532 2.0 x 105 L-929 2.7 x 105 RU
rhTNF-beta 211-TB rhTNF-beta 87/640 1.5 x 105 L-929 4.6 x 104 IU
rhTRAIL 375-TEC(E. coli) rhTRAIL 04/166 1.0 x 104 L-929 5.6 x 103 IU
rhTRAIL 375-TL(NS0) rhTRAIL 04/166 1.0 x 104 L-929 3.2 x 103 IU
rhTSH 4610-TH rhTSH 94/674 6.7 x 10-3 HEK293/h TSH R 7.9 x 10-3 RU
rhVEGF165 293-VE rhVEGF165 02/286 1.0 x 103 HUVEC 1.1 x 103 RU

* In side by side evaluation of this standard with R&D Systems product, the standard demonstrated much lower maximal signal and thus cannot be compared using ED50

**The reference material was obtained through the NIH Biodefense and Emerging Infections Research Resources Repository, NIAID, NIH.