title: Time-dependent enhancement of lymphocyte activation by mitogens after exposure to isolation or water scheduling.
abstract: The effects of isolation and water scheduling on mitogen induced lymphocyte proliferation were investigated. Isolated rats were animals which had been raised in group-housed conditions and then transferred to individual cages with ad lib access to water for a 1 or 2 week period. Water scheduled rats were maintained in group housing (5 rats per cage) with ad lib access to food but with access to water for a single 30 minute session each day. Responses of these groups were compared to those of animals which had been continuously group-housed with ad lib access to food and water. No differences in lymphocyte responses to phytohemagglutinin (PHA) were found 1 week after exposure to isolation. However, after 2 weeks, splenic and blood T lymphocytes from isolated animals demonstrated an increased proliferative response to suboptimum and maximum concentrations of PHA. Splenic B lymphocyte responses to lipopolysaccharide (LPS) from isolated animals were also increased by 2- to 3-fold compared to group-housed controls. Two weeks of exposure of animals to daily water scheduling similarly increased the splenic lymphocyte proliferation. This increased responsiveness to PHA was not accompanied by a significant change in the sensitivity of the lymphocytes to PHA, in the total number of white blood cells, or the proportion of splenic T or T helper lymphocytes. Our results show that the increase in lymphocyte proliferation is time-dependent, requires greater than 1 week of exposure to isolation and is due to factors other than changes in sensitivity to mitogen or T lymphocyte number.
authors.affiliation: Department of Pharmacology, Georgetown University Medical Center, Washington, DC 20007.
authors.forename: J J
authors.initials: JJ
authors.lastname: Jessop
authors.forename: K
authors.initials: K
authors.lastname: Gale
authors.forename: B M
authors.initials: BM
authors.lastname: Bayer
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D007958:Leukocyte Count; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008297:Male; D009929:Organ Size; D010835:Phytohemagglutinins / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012934:Social Isolation / Q000502:physiology*; D013154:Spleen / Q000033:anatomy & histology / Q000166:cytology; D013315:Stress, Psychological / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D013997:Time Factors; D014868:Water Deprivation / Q000502:physiology*
chemical_list: D008070:Lipopolysaccharides; D010835:Phytohemagglutinins