Predominant T helper 2 immune responses against Bartonella henselae in naturally infected cats.
This study was conducted to explicate the mechanism of long-term bacteremia in Bartonella henselae-infected cats by the examining host immune responses. Blood samples were collected from three naturally infected cats and the IgG antibody titers and the cytokine responses in peripheral blood mononuclear cells (PBMC) were examined by quantitative reverse transcriptase-polymerase chain reactions (RT-PCR). Relapsing bacteremia was found in two of the three cats during the examination period. The quantitative RT-PCR analyses demonstrated that increases of the mRNA expressions in interleukin-4 (IL-4) but not in gamma-interferon (IFN-gamma) were observed in PBMC from these infected cats after the bacteremia had peaked, showing that the T helper 2 (Th2) responses were specifically induced in the cats. Furthermore, the specific antibody titer increased, resulting in a decrease in the number of B. henselae to undetectable levels in these cats. However, the number of bacteria increased again in two of these cats at 90 and 45 days after the previous bacteremia, respectively. These results suggest that B. henselae predominantly induced IL-4 production from PBMC and resulted in stimulation of the humoral immune responses, including the secretion of specific antibodies in the cats. Furthermore, the specific antibody may play a role in eliminating the bacteria from cats partially but not completely, because relapsing bacteremia was found in these two cats.
Kabeya
Hidenori
H
Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-8510, Japan. kabeya@brs.nihon-u.ac.jp
Sase
Makiko
M
Yamashita
Masaya
M
Maruyama
Soichi
S
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D016470:Bacteremia / Q000276:immunology / Q000382:microbiology / Q000662:veterinary; D001474:Bartonella Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D018416:Bartonella henselae / Q000276:immunology* / Q000302:isolation & purification; D002371:Cat Diseases / Q000276:immunology* / Q000382:microbiology; D002415:Cats; D005260:Female; D015847:Interleukin-4 / Q000096:biosynthesis*; D008297:Male; D018418:Th2 Cells / Q000276:immunology*
D000907:Antibodies, Bacterial; D015847:Interleukin-4