Why Heat Incativate Serum used as a Blocking Agent?

Wendy Ingram w.ingram at uq.edu.au
Fri May 26 01:47:22 EST 2006

Why is it that protocols for immuno techniques like immunofluorescence 
that use serum as a blocking agent often stipulate that it should be 
heat inactivated?

Historically, serum for use in cell culture was heat inactivated to 
remove heat labile complement, to reduce the risk of complement 
molecules damaging cells (unnecessary these days for many sera/cell lines).

Since cells in immuno-procedures are generally dead and fixed prior to 
blocking, why is serum often heat inactivated for these protocols? Is it 
just a historical hang-up that heat inactivated sera is often used for 
blocking (since heat inactivated serum was usually handy), or is there a 
genuine reason why it should be used in preference to non-heat 
inactivated serum for immunfluorescence?

I'm keen to know the answer.


Wendy Ingram, PhD
Senior Research Officer
RCH Cancer Research Laboratory
Phone: +61 7 3636-9211
Fax:   +61 7 3365-5455
Email: w.ingram at uq.edu.au

Postal & Delivery Address:
Level 3, Foundation Building
Department of Paediatrics and Child Health
The University of Queensland
Royal Children's Hospital
Herston Rd
Herston, QLD 4029, Australia

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