Behavioral and immunological consequences of brief mother-infant separation: a species comparison.

The immediate behavioral and immunological consequences of a single 2-week maternal separation experience were studied in socially housed 7-month old bonnet and pigtail macaques. Maternal separation was associated with species dependent behavioral changes. Both species showed significant increases in ingestive behaviors associated with separation. Separated and matched controls showed an increase in disturbance behaviors (vocalization, startles, shaking, temper-tantrums) that subsided after 24-36 hours in control subjects, but continued, albeit with species-dependent patterns, in the separated monkeys. Allomaternal care of the separated bonnet infants but not the pigtail infants was associated with a progressive reduction of these disturbance behaviors during the separation period. Following a period of agitation, pigtail infants showed a depressive phase characterized by slouched, withdrawn postures and reduced motor activity. As a group, the separated infants of both species were not different from controls with respect to lymphocyte activation by mitogens, a measure of immunocompetence. However, when individual behavioral responses were considered, the change in lymphocyte activation during separation was significantly related to behavioral responses which reflected disturbance, such that the change in lymphocyte activation following in vitro stimulation with the mitogens phytohemagglutinin and Concanavalin A (markers of the immunocompetence of T lymphocytes) was related to levels of vocalization and time spent in slouched postures. The activation of B lymphocytes by pokeweed mitogen was not influenced by the separation experience nor was it associated with specific behavioral responses to separation. The importance of assessing the affective consequences of stressor is discussed.

Suppression of specific antibody production by inescapable shock: stability under varying conditions.

The effect of exposure to uncontrollable shock on the production of antibodies to a novel antigen, keyhole limpet hemocyanin (KLH), was studied in adult male Sprague-Dawley rats. Groups of rats were tested under one of four experimental conditions which included testing during either the light or dark portions of their light cycles and following either one or three daily exposures to tail shock. Control subjects were immunized with KLH in the absence of shock exposure during either the light or dark phases of their light cycle. A tertiary (memory) response was evoked 60 days following the initial immunization sequence in all animals in the absence of a shock exposure. Blood samples were obtained from the tip of the tail at the time of each immunization and at 1-week intervals for 3 weeks following immunizations. Specific IgG antibodies to KLH were determined by an enzyme-linked immunosorbent assay (ELISA). All animals exposed to shock showed reduced levels of IgG antibodies to KLH regardless of the experimental conditions of shock exposure. Antibody levels were highest among animals immunized during the dark phase of their cycle for both control and shocked animals. Antibody production to a novel antigen appears to be a robust and sensitive measure for studies of modulation of immunity by behavioral factors.