Background The protective effect of breastfeeding has been linked to immunomodulating agents in human milk, including cytokines.

Objective To evaluate the possible relationship between human milk cytokine content and atopic dermatitis in breastfed term infants.

Material and methods In 114 samples of milk fed to term infants, IL-1β, IL-2, IL-4, IL-5, IL-10, IFNγ, TGF-β1 and TNF content were determined by flow cytometry. Breastfeeding duration and diagnosis of atopic dermatitis were telephonically recorded at 18 months.

Results Atopic dermatitis appeared in 24 infants (21%). No allergies were recorded in 89 (78%). We found no significant differences in maternal age (34.8 ± 2.7 vs 34.7 ± 3.6 years), maternal allergies (54% vs 46%), birth-weight (3288 ± 512 vs 3270 ± 586 g) or breastfeeding duration (5.7 ± 1.2 vs 5.6 ± 1.4 months). Cytokines studied were detected in the following samples of mature milk: IL-1β 25%, IL-2 42%, IL-4 23%, IL-5 17%, IL-10 28%, IFNγ 25%, TGF-β1 16% and TNF 18%. In milk fed to infants with atopic dermatitis, mean concentration of TGF-β1 was higher (428 ± 221 vs 282 ± 222 pg/ml), while that of IL-1β (2.2 ± 1.1 vs 3.6 ± 7.5 pg/ml), IL-2 (6.7 ± 3.3 vs 9.6 ± 6.8 pg/ml), IL-4 (2.0 ± 0.7 vs 4.0 ± 5.2 pg/ml), IL-5 (0.6 ± 0.3 vs 1.2 ± 0.9 pg/ml), IL-10 (1.8 ± 0.7 vs 3.8 ± 3.1 pg/ml), IFNγ (2.9 ± 4.2 vs 5.9 ± 9.1 pg/ml) and TNF (2.2 ± 0 5 vs 5.4 ± 7.1 pg/ml) was lower, although differences were only significant for IL-10 (p = 0.02).

Conclusions The results suggest a possible relationship between human milk IL-10 content and atopic dermatitis in infants. However, wide variability in cytokine concentration means the sample size must be increased to draw definitive conclusions.