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Adrenocortical and behavioral predictors of immune responses to starting school
W T Boyce1, S Adams, J M Tschann
1Division of Behavioral and Developmental Pediatrics, University of California, San Francisco 94143-0314, USA.
Insights
Starting kindergarten is a stressor that impacts children's immune systems, affecting cortisol levels, behavior, and immune cell counts. Greater stress reactivity in children leads to altered immune cell numbers and antibody responses.
Area of Science:
- Psychoneuroimmunology
- Developmental Psychology
- Immunology
Background:
- Previous research links major psychological stressors to immune function.
- Few studies have examined immune changes related to minor, normative stressors like starting school.
Purpose of the Study:
- To investigate adrenocortical and behavioral predictors of immune responses in children starting kindergarten.
- To assess immune changes (T cells, B cells, antibody responses) in relation to cortisol levels and behavioral difficulties.
Main Methods:
- 39 five-year-old children provided blood samples before and after starting kindergarten.
- Salivary cortisol and immune responses (T cells, B cells, antibody titers) were measured.
- Parental ratings assessed behavioral problems and adjustment challenges.
Main Results:
- Salivary cortisol levels increased post-kindergarten entry.
- CD4+ T cells increased, while lymphoproliferative responses to pokeweed mitogen (PWM) declined.
- Higher cortisol reactivity correlated with increased B cells (CD19+) but reduced antibody response.
- Behavioral difficulties were linked to declines in T and B cell subsets.
Conclusions:
- School entry acts as a stressor, elevating cortisol and behavior problems, and altering immune status.
- Children with higher adrenocortical reactivity show increased B cells but impaired antibody production.
- Increased behavioral difficulties correlate with reduced T and B cell counts.
Abstract:
Associations between major psychologic stressors and immune function have been documented in previous research, but few studies have investigated immune changes attending minor, normative stressors. This study examined adrenocortical and behavioral predictors of immune responses to starting kindergarten in 39 five-year-old children, who completed laboratory visits for venipunctures 1 wk before (time 1) and 1 wk after (time 2) school entry. At time 1, children were also immunized with pneumococcal vaccine. Immune responses were measured as change scores for T (CD4+ and CD8+) cells, B (CD19+) cells, lymphoproliferative responses to pokeweed mitogen (PWM), and type-specific pneumococcal antibody responses (ABR). Adrenocortical response was assessed as the change in salivary cortisol level, and behavioral difficulty with school adjustment was scored using parental ratings of behavior problems, stress due to changes in routines, and degree of adaptive challenge. Salivary cortisol rose after kindergarten entry (means = 0.39 +/- 0.28 to 0.49 +/- 0.36 micrograms/dL, p = 0.03) and was unrelated to behavioral difficulties. CD4+ cells increased in number, whereas PWM declined, and CD19+ cells showed a borderline increase. Change in salivary cortisol was positively associated with change in CD19+ (delta CD19+) and inversely related to ABR. Scores for behavioral difficulty were inversely associated with delta CD4+ and delta CD19+. These data suggest that: 1) school entry is a stressor capable of evoking elevations in cortisol and behavior problems, accompanied by shifts in functional and enumerative measures of immune status; and 2) children with greater adrenocortical reactivity have increases in B cell numbers and less effective B cell-mediated antibody production, whereas children with more behavioral difficulties show declines in all T and B cell subsets.