Figure 1.

Antibiotic exposure during early life reduces Peyer’s patch hematopoietic cells and lymphocytes at day of life 20

(A) 5-day-old pups were dosed with azithromycin (AZM) (30 mg/kg of body weight), amoxicillin (AMOX) (100 mg/kg of body weight), or water as a control (CTRL). Antibiotics were prepared as a suspension in water and administered orally via a pipette tip once a day for 5 days (volumes were adjusted based on each pup’s body weight to ensure the same dose was given). Mice were sacrificed when they were 20 days old (P20).

(B) Visible Peyer’s patches were counted along the length of the entire small intestine. Single-cell suspensions of Peyer’s patches were prepared for staining with fluorescently tagged antibodies.

(C) Flow cytometry plots showing the P20 Peyer’s patch live CD45⁺ cell populations after gating on lymphocytes and singlets.

(D) Live CD45⁺ cell counts from the same representative flow plots shown in panel C.

(E) B cell counts from the same samples; B cells were defined as CD19⁺B220⁺ cells. All data shown are from a single representative experiment of two independent experiments; panel B shows the median, and D and E show the mean value ±standard error of mean (SEM); ∗ indicates p < 0.05, ∗∗p < 0.01.