Humoral immune response induced by the protein core of MUC1 mucin in pregnant and healthy women*

Serum levels of MUC1 and antibodies (Abs) against MUC1 (IgG and IgM-MUC1) were evaluated in healthy women related to pregnancy and lactation status. A total of 149 serum samples were obtained from: nulliparous, primiparous pregnant, multiparous pregnant that have lactated, multiparous pregnant without lactation, multiparous non-pregnant actual lactating, multiparous non-pregnant that have lactated and finally, multiparous non-pregnant women without lactation. In all assays, we included pre- and post-serum samples belonging to a breast cancer patient vaccinated with a MUC1 derived peptide. CASA test was employed to measure MUC1 while IgG- and IgM-MUC1 serum Abs were evaluated with an ELISA using a 100 mer peptide as catcher. In all groups, mean IgM levels were higher than IgG mean values; when samples were grouped in pregnants versus non-pregnants, a significant difference was detected with both Abs, being raised in non-pregnants. When samples were grouped in lactating versus non-lactating a significant difference was detected with IgG-MUC1, being raised in lactating women while no significant difference was found with IgM-MUC1. The evaluation of serum MUC1 levels confirmed previous results since a significant difference between pregnant versus non-pregnant groups was found while lactating versus non-lactating samples did not. Conclusions: (i) Increased MUC1 serum levels are apparently associated with pregnancy but not with lactation; (ii) MUC1 Abs are mainly associated with lactation and with non-pregnant status. These results may be considered a contribution on studies about protection against breast cancer induced by pregnancy and lactation.