Individual differences in cell-mediated and humoral immunity in pigs

Previous experiments displayed consistent individual behavioural differences in pigs. Some showed a more active behavioural response (aggressive and resistant; so-called AR pigs), others a more passive behavioural response (non-aggressive and non-resistant; so-called NANR pigs). Moreover, these behavioural coping strategies were associated with different behavioural, physiological and endocrine responses under stress conditions. In the present study we selected 32 AR and 32 NANR individuals and tested their immune reactivity in reaction to stress using several cell-mediated (CMI) and humoral immunological tests. Active AR pigs had a higher in vivo and in vitro CMI to nonspecific and specific antigens, while after stress CMI reduced more in AR than in NANR pigs. In contrast, humoral immunity was highest in NANR pigs. Furthermore, some serologically typed swine lymphocyte antigen (SLA) class I haplotypes were not equally distributed between AR and NANR pigs. In general, these findings show that measurement of immune reactivity is an important tool to define how animals cope with environmental demands.