A diminished mucosal concentration of
secretory immunoglobulin A (
sIgA) in the upper respiratory tract may increase susceptibility to colds and flu. The aim of the present study was to determine whether
sIgA increases during relaxation in children aged between 8 and 12 years with recurrent
upper respiratory tract infections. Forty-five healthy children and 45 children with 10 or more
upper respiratory tract infections in the previous year were randomly assigned to one of three experimental conditions: relaxation with suggestions to increase immune system
proteins, relaxation alone, or a control condition. Samples of saliva were obtained before and after each condition. The concentration of
sIgA in the saliva samples was later determined by measuring the rate of precipitation of
antigen-antibody complexes to known concentration of
sIgA antigen. The concentration of
sIgA increased in the relaxation conditions but not in the control condition. The
sIgA/
albumin ratio (a more specific measure of local mucosal immunity than concentration) increased during the relaxation-suggestion condition but not during the relaxation or control conditions; however, both the concentration of
sIgA and the
sIgA/
albumin ratio increased in proportion to subjective relaxation ratings. Neither response differed between healthy children and children with
recurrent infections. The findings indicate that a disturbance in mucosal immunity in children with recurrent colds and flu does not limit increases in
sIgA during relaxation. Higher preinfection levels of
sIgA correlate with resistance to
upper respiratory tract infection, so enhancing the
sIgA concentration with
relaxation techniques may help children with
recurrent infection problems.