Background: Cellular proliferation to various allergens (Dermatophagoides pteronyssinus, beta-lactoglobulin, bovine serum albumin, ovalbumin) has been found in cord blood cells. Whether this reflects a sensitization during foetal life is uncertain.
Objective: We studied the cellular reactivity and cytokine production of cord blood cells in response to cow's milk proteins in a randomly selected group of newborns. The delineation of possible in utero allergen contact was attempted.
Methods: Cord blood mononuclear cells from 39 neonates were incubated with cow's milk proteins (alpha-lactalbumin, beta-lactoglobulin, casein, alpha-casein, beta-casein, kappa-casein, bovine serum albumin) for 7 days, and proliferation was assessed by incorporation of [3H]thymidine. Cord blood cell-derived interferon-gamma (IFN gamma) and interleukin-4 (IL-4) secretion was evaluated in response to allergen or phytohaemagglutinin (PHA) stimulation.
Results: A pronounced proliferation of cells stimulated with alpha-lactalbumin (ALA: mean stimulation index 8.0, 95% confidence interval 5.2-10.8), beta-lactoglobulin (BLG: mean stimulation index 5.9, 95% confidence interval 3.2-8.6) and alpha-casein (2.6, 95% confidence interval 2.9-9.1), as opposed to unstimulated cells in medium, was found. No correlation was found between cellular proliferation to milk proteins and parental atopy, maternal total IgE or cord blood IgE. IFN gamma production (but not IL-4) was inducible by PHA (range 429-1810 pg/ml), but only in one individual upon stimulation with BLG. Preferentially, reduced IFN gamma levels were found in individuals with positive parental allergic history.
Conclusion: The recognition of allergen by cord blood cells indicates that allergen priming must occur prenatally. The relevance for subsequent sensitization is unclear.