BACKGROUND: When feeding preterm infants, donor milk is preferred if the 
mother's own milk is unavailable. Pasteurization may have detrimental effects on 
bioactivity, but more information is needed about its effects on the 
immunological compounds. Research aim: This work has two main aims: evaluate the 
antibody profile of colostrum and study the quantitative variations in the 
antibodies' level and specific reactivity after undergoing Holder 
pasteurization. The authors focused on immunoregulatory components of colostrum 
(antidietary antibodies and TGF-β2) in the neonatal gut.
METHODS: This is a descriptive cross-sectional study of a convenience sample of 
67 donated colostrum samples at different days after delivery, both raw and 
pasteurized. Antibody profiles were analyzed at different times during 
breastfeeding, and total and specific antibodies (IgM, IgA, and IgG subclasses) 
were compared with tetanus toxoid and ovalbumin using enzyme-linked 
immunosorbent assay. The processing effect on total and specific antibodies, as 
well as TGF-β2, was evaluated by paired analyses.
RESULTS: No variations in immunological compounds were observed throughout the 
colostrum stage. The TGF-β2, antibodies' concentrations, and antibodies' 
specific reactivity after pasteurization did not vary significantly as days of 
lactation varied. Changes in antibody levels were dependent on isotype and IgG 
subclass, and IgG4 showed remarkable resistance to heating. Moreover, the effect 
of the pasteurization on specific reactivity was antigen dependent.
CONCLUSION: The supply of relevant immunological components is stable throughout 
the colostrum stage. The effects of pasteurization on antibodies depend on 
isotype, subclass, and specificity. This information is relevant to improving 
the immunological quality of colostrum, especially for preterm newborns.