Experimental timeline of the ovalbimin (OVA)-sensitized BALB/c mouse model.

<p>Six-week-old female BALB/c mice were fed with heat-killed <i>Lactobacillus plantarum</i> K37 (K37) for 4 weeks and intraperitoneally injected three times at days 1 and 14 with 50 µg of OVA in 100 µL of Al(OH)₃. On days 28, 29 and 30, the mice were challenged with OVA (1% in PBS, 100 µL/mouse) or PBS by intranasal administration. Serum was collected weekly for immunoglobulin (Ig) measurement. On day 34, mice were sacrificed and spleens were removed for spleen cell preparation.