Increased interferon-gamma- and interleukin-4-synthesizing subsets of circulating T lymphocytes in pregnant asthmatics.

BACKGROUND: Pregnancy frequently interferes with the course of bronchial asthma, and asthmatic pregnant women experience less successful pregnancies. T lymphocytes synthesizing IL-4 or IFN-gamma are important in allergic mechanisms of the airways as well as in materno-fetal immunity.
OBJECTIVE: We hypothesized that pregnancy (a T helper-2 polarized state) of asthmatics will enhance the number of circulating T2 lymphocytes, but decrease the subset-producing IFN-gamma (T1 lymphocytes) and thereby cause a culminating T2 dominance with possible clinical consequences.
METHODS: IL-4- or IFN-gamma-producing T lymphocytes were determined by flow cytometry in healthy (n=8) and asthmatic (n=13) non-pregnant women and healthy (n=18) and asthmatic (n=48) pregnant women of similar chronological and gestational (2nd-3rd trimester) age and asthma severity (Global Initiative for Asthma II-III).
RESULTS: In the blood of non-pregnant women--healthy or asthmatic--the numbers of IL-4- and IFN-gamma+ T cells were very low (<10/microL blood). In contrast, in asthmatic pregnant women, the cell counts were 182+/-27 and 39+/-6 for IFN-gamma+ and IL-4+ T cells/microL blood, respectively (both P<0.05 vs. respective control values of non-pregnant asthmatics). Within the asthmatic pregnant group, significant negative correlations were revealed between the numbers of IFN-gamma+ or IL-4+ T cells and maternal peak expiratory flow as well as birth weight of newborns (both P<0.05).
CONCLUSION: These data show a previously unknown immunological interference between asthma and pregnancy. The culminating proliferation of IFN-gamma+ and IL-4+ T lymphocytes may potentially impair maternal airway symptoms as well as fetal development.