Persistent lack of human herpesvirus-6 specific T-helper cell response in liver transplant recipients.
BACKGROUND
Specific immunologic defects predisposing to human herpesvirus-6 (HHV-6), e.g. the role of HHV-6 specific T-helper cell memory response in liver transplant recipients, have not been assessed.


METHODS
T-helper function (mitogen ConA response) as a marker of overall immunocompetence and T-helper response (memory response) specific to HHV-6 and cytomegalovirus (CMV) were assessed in 15 liver transplant recipients and compared with 25 healthy subjects. Samples were tested pretransplant, at 2 weeks, 1 month, 2-3 months, and 1 year posttransplantation. Stimulation index (SI) >3 was considered a positive response.


RESULTS
Seven percent (1/15) of the transplant recipients at any time posttransplantation, as compared to 64% (16/25) of the healthy subjects, had a positive HHV-6 memory response (P = 0.00065). HHV-6-specific memory response in transplant recipients at 2 weeks (SI 1.43), 1 month (SI 1.1), and 2-3 months (SI 1.3) was significantly more suppressed than in healthy subjects (SI 17.5, P = 0.0001). Although transplant recipients as compared to healthy subjects also had a lower CMV-specific memory response posttransplant (P = 0.0439), CMV-specific memory response recovered significantly at 1 month (P = 0.03) and at 2-3 months (P = 0.027) as compared to that at 2 weeks. However, HHV-6 memory response was persistently absent up to 2-3 months with partial recovery at 1 year; 7% of the patients at 2-3 months, but 25% at 1 year had a positive HHV-6 specific memory response. Forty percent (6/15) of the patients developed HHV-6 viremia a mean of 4 weeks posttransplant. Patients with HHV-6 viremia had greater suppression of HHV-6 memory response at 1 month than those without viremia (mean SI, 0.96 vs. 1.3, P = 0.08). All but one of the patients had a positive ConA response.


CONCLUSIONS
Prolonged suppression of HHV-6 memory response, but not overall T-helper cell function was documented and may play a role in the pathogenesis of HHV-6 infection in liver transplant recipients. Memory response to CMV after liver transplantation was significantly more robust than to HHV-6.
Singh
Nina
N
Infectious Disease Section, VA Medical Center, University Drive C, Pittsburgh, PA 15240, USA. nis5+@pitt.edu
Bentlejewski
C
C
Carrigan
D R
DR
Gayowski
T
T
Knox
K K
KK
Zeevi
A
A
D015654:Herpesvirus 6, Human / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D016031:Liver Transplantation / Q000276:immunology*; D008213:Lymphocyte Activation; D009894:Opportunistic Infections / Q000150:complications / Q000276:immunology; D019349:Roseolovirus Infections / Q000150:complications / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D014766:Viremia / Q000150:complications / Q000276:immunology