Socioeconomic status, stress, and immune markers in adolescents with asthma.

OBJECTIVE Previous research has demonstrated links between low socioeconomic status (SES) and clinical asthma outcomes, as well as links between stress and asthma. The objective of this study was to test whether adolescents with asthma from different SES backgrounds differed in biological profiles relevant to asthma, including immune and cortisol measures. The second objective was to test whether psychological stress and control beliefs could explain these differences. MATERIALS AND METHODS Adolescents with persistent asthma from either low (N= 18) or high (N= 12) SES neighborhoods were interviewed about their stress experiences (chronic stress, acute life events, interpretations of ambiguous life events) and control beliefs. Blood was drawn to assess immune (cytokines, eosinophils, IgE) and neuroendocrine (cortisol) markers associated with asthma. RESULTS Adolescents in the low SES group had significantly higher levels of a stimulated cytokine associated with a Th-2 immune response (IL-5), higher levels of a stimulated cytokine associated with a Th-1 immune response (IFN-gamma), and marginally lower morning cortisol values compared with the high SES group. Low SES adolescents also had greater stress experiences and lower beliefs about control over their health. Statistical mediational analyses revealed that stress and control beliefs partially explained the relationship between SES and IL-5/IFN-gamma. CONCLUSION Our finding that low SES was associated with elevations in certain immune responses (IL-5/IFN-gamma) in adolescents with asthma suggests the importance of further exploration into relationships between SES and Th-2/Th-1 responses in asthma. Our findings also suggest that psychological stress and control beliefs may provide one explanation for links between SES and immune responses in childhood asthma.