title: Reduced primary antibody responses in a genetic animal model of depression.
abstract: OBJECTIVE
  Clinical depression is associated with multiple abnormalities of immune function, including reduced virus-specific responses. This study tested the hypothesis that the Flinders Sensitive Line (FSL) rat, a promising genetic animal model of depression, would exhibit reductions in antigen-specific primary antibody responses to immunization.
  
  
  METHODS
  FSL (N = 13) and control Flinders Resistant Line (FRL; N = 14) rats were immunized with the protein antigen keyhole limpet hemocyanin (KLH; 300 microg/kg), and KLH-specific immunoglobulin (Ig)M, IgG, IgG1, and IgG2a responses were measured before and 3, 5, 7, 11, and 14 days after immunization. In separate experiments, production of interferon-gamma (IFN-gamma) by cells from naive and KLH-immunized animals was measured in vitro to determine whether strain differences in antibody production might be associated with differential production of this regulatory cytokine.
  
  
  RESULTS
  KLH-specific production of IgM (p <.01) and IgG2a (p <.05) was significantly reduced in the FSL rats compared with the FRL controls. There were no strain differences in IgG or IgG1 production. Although IFN-gamma production between the two strains was similar in naive animals, cells from KLH-immunized FSL rats produced significantly less IFN-gamma when stimulated with KLH in vitro than cells from KLH-immunized FRL controls (p =.01).
  
  
  CONCLUSIONS
  This study extends previous reports of altered immune function in the FSL rats to include reduced in vivo antigen-specific antibody responses. Moreover, diminished production of IFN-gamma by KLH-primed lymphocytes may contribute to lower antibody production in these animals. Collectively, these data suggest deficiencies in type 1 T-helper cell-mediated immunity in the FSL rats.
authors.affiliation: Psychology Department, Bronfman Science Center, Williams College, Williamstown, MA 01267, USA. Elliot.M.Friedman@williams.edu
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Friedman
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Becker
authors.forename: David H
authors.initials: DH
authors.lastname: Overstreet
authors.forename: David A
authors.initials: DA
authors.lastname: Lawrence
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000235:genetics* / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D003866:Depressive Disorder / Q000235:genetics / Q000276:immunology*; D006433:Hemocyanins / Q000276:immunology; D006801:Humans; D008297:Male; D008957:Models, Genetic; D051381:Rats; D011919:Rats, Inbred Strains; D018417:Th1 Cells / Q000276:immunology
chemical_list: D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin