Nirvana
11-08-09, 06:00 AM
http://cme.medscape.com/viewarticle/565696
People are getting booster shots when their immunity levels most likely do not require it, according to the results of a longitudinal study reported in the November 8 issue of the New England Journal of Medicine.
"Maintenance of long-term antibody responses is critical for protective immunity against many pathogens," write Ian J. Amanna, PhD, from the Oregon Health & Science University in Beaverton, and colleagues. "However, the duration of humoral immunity and the role played by memory B cells remain poorly defined. To address the issue of antibody maintenance after infection or vaccination, we conducted a longitudinal analysis of antibody titers against multiple antigens with the use of serum samples banked from a combination of scheduled (annual) and event-based collections."
For a period of up to 26 years, 45 subjects underwent longitudinal analysis of antibody titers specific for viral antigens (vaccinia, measles, mumps, rubella, varicella-zoster virus, and Epstein-Barr virus) and nonreplicating antigens (tetanus and diphtheria). The investigators also measured antigen-specific memory B cells using limiting-dilution analysis, and they compared memory B-cell frequencies with their corresponding serum antibody levels.
Half-lives for antibody titers ranged from approximately 50 years for varicella-zoster virus to greater than 200 years for other viruses, including measles and mumps, suggesting remarkable stability of antiviral antibody response. Estimated half-lives were shorter for antibody responses against tetanus and diphtheria antigens (11 and 19 years, respectively). Although B-cell memory was long-lived, peripheral memory B-cell numbers and antibody levels were not significantly correlated for 5 of the 8 antigens tested.
"These studies provide quantitative analysis of serologic memory for multiple antigens in subjects followed longitudinally over the course of more than one decade," the study authors write. "In cases in which multiple exposures or repeated vaccinations were common, memory B-cell numbers did not correlate with antibody titers. This finding suggests that peripheral memory B cells and antibody-secreting plasma cells may represent independently regulated cell populations and may play different roles in the maintenance of protective immunity."
Limitations of the study include possible unrecognized confounders that may affect humoral immunity, resulting in more rapidly decaying antibody responses than those observed.
"Our findings are based on T-cell–dependent antibody responses, and the mechanisms involved in antibody persistence may differ for humoral immunity against T-cell–independent antigens, which is often short-lived," the study authors conclude. "Greater insight into the factors that determine the duration of specific antibody responses will be important for future vaccine design, as well as for determining the timing of booster vaccinations required to sustain protective levels of immunity."
The Public Health Service supported this study. The authors have disclosed no relevant financial relationships.
N Engl J Med. 2007;357:1903-1915.
Clinical Context
Maintenance of long-term immunity is critical to protection against infectious diseases, and immunization or infection often confers lifelong immunity, but the degree and duration of antibody maintenance after immunization or exposure for various antigens and nonreplicating antigens is unclear.
This is a prospective longitudinal study following antibody titers of patients who provided serum during a period of up to 25 years to examine the immunity conferred by immunization and natural exposure to infection with viral antigens and nonreplicating antigens.
People are getting booster shots when their immunity levels most likely do not require it, according to the results of a longitudinal study reported in the November 8 issue of the New England Journal of Medicine.
"Maintenance of long-term antibody responses is critical for protective immunity against many pathogens," write Ian J. Amanna, PhD, from the Oregon Health & Science University in Beaverton, and colleagues. "However, the duration of humoral immunity and the role played by memory B cells remain poorly defined. To address the issue of antibody maintenance after infection or vaccination, we conducted a longitudinal analysis of antibody titers against multiple antigens with the use of serum samples banked from a combination of scheduled (annual) and event-based collections."
For a period of up to 26 years, 45 subjects underwent longitudinal analysis of antibody titers specific for viral antigens (vaccinia, measles, mumps, rubella, varicella-zoster virus, and Epstein-Barr virus) and nonreplicating antigens (tetanus and diphtheria). The investigators also measured antigen-specific memory B cells using limiting-dilution analysis, and they compared memory B-cell frequencies with their corresponding serum antibody levels.
Half-lives for antibody titers ranged from approximately 50 years for varicella-zoster virus to greater than 200 years for other viruses, including measles and mumps, suggesting remarkable stability of antiviral antibody response. Estimated half-lives were shorter for antibody responses against tetanus and diphtheria antigens (11 and 19 years, respectively). Although B-cell memory was long-lived, peripheral memory B-cell numbers and antibody levels were not significantly correlated for 5 of the 8 antigens tested.
"These studies provide quantitative analysis of serologic memory for multiple antigens in subjects followed longitudinally over the course of more than one decade," the study authors write. "In cases in which multiple exposures or repeated vaccinations were common, memory B-cell numbers did not correlate with antibody titers. This finding suggests that peripheral memory B cells and antibody-secreting plasma cells may represent independently regulated cell populations and may play different roles in the maintenance of protective immunity."
Limitations of the study include possible unrecognized confounders that may affect humoral immunity, resulting in more rapidly decaying antibody responses than those observed.
"Our findings are based on T-cell–dependent antibody responses, and the mechanisms involved in antibody persistence may differ for humoral immunity against T-cell–independent antigens, which is often short-lived," the study authors conclude. "Greater insight into the factors that determine the duration of specific antibody responses will be important for future vaccine design, as well as for determining the timing of booster vaccinations required to sustain protective levels of immunity."
The Public Health Service supported this study. The authors have disclosed no relevant financial relationships.
N Engl J Med. 2007;357:1903-1915.
Clinical Context
Maintenance of long-term immunity is critical to protection against infectious diseases, and immunization or infection often confers lifelong immunity, but the degree and duration of antibody maintenance after immunization or exposure for various antigens and nonreplicating antigens is unclear.
This is a prospective longitudinal study following antibody titers of patients who provided serum during a period of up to 25 years to examine the immunity conferred by immunization and natural exposure to infection with viral antigens and nonreplicating antigens.