*2.4. Milk/egg IgE Sensitization*

SPT with cow's milk, casein, egg white, egg yolk (Lofarma, Milano, Italy), fresh cow's milk, fresh egg white, Pavesini, and Biscottino Primi Mesi were performed. In this case, 10 mg/mL histamine phosphate in 50% glycosaline and glycosaline on its own (Lofarma, Milano, Italy) were used as positive and negative controls, respectively. A Dome-Hollister-Stier lancet with a 1 mm tip was used for the procedure. Wheal diameters were read through a clear plastic calliper disk scaled in mm under × 4 magnification, and were interpreted when the wheal margin was included within a complete caliper circle to the nearest mm [18]. A limit of 5 mm was set for SPT positivity.

Ten mL of venous blood was collected from the patients to determine serum IgE levels (total and specific for cow's milk proteins, casein, egg white, egg yolk) using ImmunoCAP® (Thermo Fisher Scientific, Waltham, MA, USA), with 0.35 kU/L as a lower limit of eligibility [19]. Part of the serum was stored at –80 ◦C for successive protein sensitivity evaluations.
