The aim of the present study was to examine the influence of daily positive and negative mood on secretory immunoglobulin A (S-lgA) concentrations in human saliva. An instrument was constructed for the measurement of daily mood, based on current theories in the psychobiology of affect, neuroendocrinology and behaviour. With this instrument the average intensity, peak intensity and duration of eight moods, two from each pole of positive and negative affect dimensions, were measured. From these scores three positive affect variables were created by combining scores on positive dimension moods, and three negative affect variables created by combining scores on negative dimension moods, and these variables were used for multivariate analysis. Twenty female subjects between the ages of 18 and 60 years were studied for 28 consecutive days. They were each required to capture 1.5 ml of free flowing parotid saliva, fill in the mood questionnaire, and record whether or not they had taken medication, exercise, alcohol, tobacco or menstruated on each evening of the study. These last variables were subsequently used as control variables in the multivariate analysis. Concentrations of S-lgA in the saliva were measured with an enzyme-linked immunosorbent assay (ELISA).
No significant associations between S-lgA levels and positive or negative mood variables were detected. The lack of significant effects of mood variables on S-lgA is discussed in the context of the psychoneuroimmunological literature, and with particular emphasis on measurement issues.