The protective factors of breast milk are known to be associated with:

Breastmilk contains mainly secretory IgA, which has a specific antigen-targeted anti-infective action. Other protective factors include macrophages, lymphocytes, lactoferrin, lysozyme, Bifidus factor, and interferon. But, as IgA plays a major role, it is the best answer here. Components Of breast milk and diseases they protect against: Components of breast milk Protection against Lysozyme Escherichia coli, Salmonella Entamoeba histolytica Lactoferrin E.coli, Shigella, Salmonella E.histolytica, Giardia lamblia Plasmodium falciparum Rotavirus Bifidus factor E.coli, Shigella, Salmonella Low levels of para-amino benzoic acid Plasmodium Ref: Ghai Essential Pediatrics 9th edition Pgno: 145