Vaccine
Adjuvant in Immunocompromised Patients
Immune senescence, a normal aging process, has been related
to a gradual decline in thymus function and thymic hormone production.
The lack of thymic hormones may contribute to the decline in
immune function, particularly the T-cell component. (112-114)
In the elderly, quantitative and qualitative analysis of a specific
antibody response after vaccination has been shown to be compromised
when compared with response in young subjects. (115,116)
Decreased antibody response to T-cell dependent antigens may
be one factor that accounts for insufficient efficacy of certain
vaccination programs (eg, influenza). Diminished antibody responses
have also been reported in patients with end-stage renal disease.
The evidence for impairment of cellmediated immunity in hemodialysis
patients has been attributed to incompetence in T-cell–mediated
immune responses. (117-121) Several
studies have reported poor antibody response after hepatitis
B vaccination in hemodialysis patients. (122-124)
Since Zadaxin can enhance T-cell-dependent specific antibody
production, the addition of Zadaxin to vaccination programs
for immunocompromised individuals should be effective. In vaccinated
elderly individuals, in vitro influenza antibody synthesis was
augmented with the addition of Zadaxin. (115)
Enhancement of specific antibody responses to tetanus toxoid
and sheep red blood cells also was observed by the in vivo administration
of Zadaxin to older mice or mice immunosuppressed with cocaine.
(125,126) These experimental
data support that Zadaxin, when appropriately administered with
a vaccine, can enhance immune function and enhance an antibody
response in individuals with a compromised immune system.
Six clinical studies have been completed that evaluated the
efficacy of Zadaxin as an adjuvant for influenza and hepatitis
B antiviral vaccines in subjects immunocompromised due to age
or hemodialysis. When compared with vaccine plus placebo, administration
of Zadaxin in conjunction with vaccine increased and sustained
the specific antibody response, increased protection against
illness, and overcame previous lack of specific antibody response
and age-associated decline in specific antibody response. The
studies also show that Zadaxin is safe for administration to
immunocompromised subjects, and no serious adverse effects were
observed in any of the studies.
Back to top
|
