2008 PBL Cat_mech_r.qxd:PBL Catalog.mech 11/29/07 1:51 PM Page 50
FAQs by Product
QUESTION ANSWER
Interferon
1.1) Level of endotoxin? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Endotoxin levels are <1 EU/µg.
1.2) The difference between carrier protein and carrier free? . . . . . . Carrier protein (PBS with 0.1% BSA) was added to provide extra stability
to the sample. However, in certain applications such as in vivo injection,
conjugation, or surface binding, carrier protein may interfere.
1.3) How to convert interferon specific activity to mass? . . . . . . . . . The formula to use to convert S.A. to pg/ml is as follows:
[(1x 10
9
)/(Lot specific activity in units per mg)] x (Lot Concentration
in units per ml)
1.4) Why is human interferon beta shipped in acetic acid? . . . . . . . . Acetic acid prevents aggregation of interferon beta proteins.
1.5) What dilution buffer should I use upon receiving the sample? . . . PBS with 0.1% BSA.
Antibodies
2.1) How much neutralizing antibody should I use? . . . . . . . . . . . . . . User cell lines may vary so there is no specific answer to this question.
However, the general rule is a 70 fold excess in mass should be used
for neutralizing interferon. It is recommended to quantify the amount
of interferon via techniques such as ELISA. It is also recommended to
allow time (1-2 hours in general) for the antibody to neutralize the
interferon before adding the virus.
2.2) What controls should I use? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . For monoclonal antibodies, use normal antibody from the same species
and the same isotype. For example, if a MAb is a murine IgG
2A
, use the
normal equivalent as the negative control.
PBL’s polyclonal antibodies are unpurified sera. Therefore, investigators
should use normal unpurified serum from the appropriate species as
their negative control.
2.3) Does PBL offer controls for its antibodies? . . . . . . . . . . . . . . . . . . PBL does not offer any controls for our antibodies at the current time.
2.4) How are antibodies determined to be neutralizing? . . . . . . . . . . The viral challenge assay is used to test antibodies for neutralization
activity. The assay measures the ability of the antibody to negate the
protective affects of the interferon against the viral challenge.
ELISA
3.1) What types of antibodies are used in the ELISA kits? . . . . . . . . . All PBL ELISA kits are constructed with carefully selected proprietary
antibodies and optimized reagents.
3.2) What are the specifications for optimization of the . . . . . . . . . . To optimize each lot of kits, PBL modifies the concentration of the
reagents for each lot of the kits? reagents to achieve a standard curve that will meet our specific range
and signal to noise requirements.
3.3) Does PBL offer ELISA reagents separately? . . . . . . . . . . . . . . . . . . PBL does not offer reagents separately.
3.4) Can components from different lots be used as substitutes? . No. Reagent concentration is optimized according to lot. Reagents from
different lot can not be used as substitutes.
3.5) Can I use serum or plasma in your ELISA kits? . . . . . . . . . . . . . . . With the exception of VeriKine
TM
Human Interferon Alpha Multi-Subtype
Serum ELISA kits (PBL product #41110-1 and #41110-2), and VeriKine
TM
Mouse Interferon Beta ELISA kits (PBL product #42400-1 and #42400-
2), all other PBL ELISA kits have not been evaluated for use with serum
sample.
PBLInterferonSource Toll Free: 1 877- PBL-8881
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