Biological Psychology/Pharmacopsychology Main Editor: P. Netter (Giessen) Original Paper Neuropsychobiology 1998;38:90–96 Lymphocyte Response to Mitogens: Influence of Life Events and Personality M.I. Gonza ´ lez-Quijano a M. Martı´n b S. Milla ´n c A. Lo ´ pez-Caldero ´n c Dpts. a Enfermerı ´a, b Psiquiatrı ´a y Psicologia Médica and c Fisiologı ´a, Universidad Complutense, Madrid, Spain OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO Key Words Cellular immunity Life event stress Lymphocyte proliferation Mitogens Personality traits OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO Abstract The aim of the present study was to examine the possibility that the accumula- tion of life events is associated with low lymphoproliferative response to mito- gens in undergraduate students. We also analyzed the possible interaction between life events and personality traits. Lymphocyte response to phytohe- magglutinin (PHA) was lower in subjects with high life events compared to those with low levels. Introverted subjects were found to exhibit lower lym- phocyte responses to PHA than those who were extraverted, and there was no interaction between the effect of introversion and life events on the prolifera- tive capacity. Lymphocyte proliferation was low in subjects with high anxiety scores, whether they had high or low levels of life events. In the group with high scores on independence a high accumulation of life events was not associ- ated with lower lymphoproliferation; while in the group with low scores it was, suggesting that independence buffers the association between life stress and lower cellular immunity. OOOOOOOOOOOOOOOOOOOOOO M.I. Gonza ´ lez-Quijano Escuela Univesitaria de Enfermerı ´a, Fisioterapia y Podologı ´a Facultad de Medicina, Pabello ´ n 2, 3 a planta, Ciudad Universitaria E–28040 Madrid (Spain) Tel. +34 1 3941545, Fax +34 1 3941539 ABC Fax + 41 61 306 12 34 E-Mail karger@karger.ch www.karger.com © 1998 S. Karger AG, Basel 0302–282X/98/0382–0090$15.00/0 Accessible online at: http://BioMedNet.com/karger Introduction There is increasing interest in the role that stressful or adverse life situations play in the etiology of physical dis- ease. Much evidence shows that the effect of chronic stress on infectious and autoimmune diseases as well as on some types of cancer is mediated by immunological changes [1–9]. Alterations in immune functions have been found in people after bereavement, divorce, unem- ployment [10], surgical stress [11], academic stress [12, 13], natural disasters [14] and in those providing care for relatives suffering from mental illness [15–17]. Further- more, the simple accumulation of life changes is associat- ed with further development of somatic illnesses [18]. Responses to stressors show considerable variability among individuals, but the mechanisms responsible for this variability are not well known. Personality structure can be considered as a source of interindividual variance, and links between some personality types and increased risk of developing certain illnesses have been found [19, 20]. Exaggerated pleasantness, perfectionism, social con- formism, avoidance of conflict, suppression and repres- sion of feelings and emotions, in particular anger and hos- tility, and rigid control or defensiveness are associated with increased incidence of cancer [19]. McClelland et al. [21] found lower IgA concentrations and a high frequency