Heat inactivation of FBS is a practice routinely observed in most cell culture labs across the globe. Its wide applicability has come to draw on it more as a customary protocol and less as a standing scientific principle. However, during its original conception, the main purpose behind the heat inactivation of FBS revolved around immune complements intolerant to heat. Observations showed that FBS contained negligible amounts of such complement, and that these complements had no bearings on hemolytic, even in undiluted serum. Nonetheless, these complements were destroyed when the serum was thawed at 37ºC in the prepping processes.

Complement proteins and a number of other crucial substances in the serum become diminished when the serum is subjected to heat inactivation. Since these complements are key determinants of the host’s performances immunity-wise, their degradation has wide implications relevant to immunological studies. Heat inactivation of FBS significantly diminishes the intensity with which these complements interfere in the host’s immune response, heat inactivation of FBS.

Nonetheless studies carried out by Coriell Institute shows that heat inactivation of FBS serves no purpose at all for certain types of cells. For instance, unlike the many other cell lines that thrive in heat inactivated serum, lymphoblast and fibroblast lines generate reactions that are actually indifferent to heat inactivated serum.