Antibody
Response to an Antigenic Challenge
Summary prepared by Sheldon Cohen in
collaboration with the Allostatic Load Working Group. Last revised December, 1997. Cohen
and collagues have written an expanded and more detailed treatment of this topic: Cohen,
S., Miller, G. E., & Rabin, B. S. (2001). Psychological stress and antibody response
to immunization: A critical review of the human literature. Psychosomatic Medicine, 63,
7-18.
Chapter Contents:
a. Definitions
b. Measurement
c. Physiological Mechanisms
d. Relevant Research
e. References
Definitions
The immune system responds to foreign invaders
(antigens) by producing antibodies. Antibodies are protein molecules that attach
themselves to invading microorganisms and mark them for destruction or prevent them from
infecting cells. Antibodies are antigen specific. That is antibodies produced in response
to antigen exposure are specific to that antigen.
In an in vivo test assessing the competence of the humoral arm of the immune system,
individuals are inoculated with an antigen, and the amount of antibody (Ab) produced in
response to that specific antigen is quantified. Depending on the specific type of Ab, it
can be quantified from either blood (IgG) or mucosal secretions such as saliva and nasal
discharge (IgA). The more Ab produced in response to an antigen, the more
"competent" the humoral system is assumed to be.
It is important to distinguish between primary and secondary response to an antigen
challenge. Primary response refers to the first time a persons is exposed to the antigen.
Secondary response refers to subsequent exposure. Following a primary antigenic challenge
there is an initial lag phase when no antibody can be detected. This is followed by phases
in which the antibody titre rises logarithmically to a plateau and finally declines again
as the antibodies are naturally catabolized or bind to the antigen and are cleared from
circulation. The secondary response has a shorter lag phase and an extended plateau and
decline. The plateau in secondary response is typically 10X greater than in primary
response.
Measurement
Several antigenic challenges have been used in studies of humans. These include rabbit
albumin (a nonpathogenic antigen), as well as response to vaccinations for tetanus and
hepatitis B. It is, however, possible to examine response to any antigen that can be
safely used with humans.
Physiological Mechanisms
When antigen encounters the immune system it is processed by antigen-presenting cells
which retain fragments of the antigen on their surfaces. T-helper cells recognize the
antigen via their surface receptors and provide help to B cells which also recognize
antigen by their surface receptors. The B cells are stimulated to proliferate and divide
into antibody forming cells which secrete antibody. There are a small number of antigens
(T-independent antigens) that can stimulate B cells to produce Ab without T-cell help.
Relevant Research
There are no studies that related SES to antibody response, but a number have examined
associations of antibody response (in humans) with psychological stress. All have used
Hepatitis B vaccinations. Unfortunately, these data do not provide a clear picture of the
role of stress in antibody response. Most of the studies have addressed response to
Hepatitis B vaccinations. Glaser et al (1992) failed to find a prospective relation
between negative affect and seroconversion (initial production of Hepatitis B antibodies)
in response a primary challenge (first injection). They did, however, find that those who
did not seroconvert were more stress reactive (reported more stress in response to a
subsequent exam period) than those who did seroconvert. The other studies have all
examined secondary response. Jabaaij et al (1993) found that greater perceived stress
assessed after the second Hepatitis B vaccination was associated with less antibody
production (among those who had already seroconverted) in response to the third injection.
It is unclear, however, whether these differences in antibody level are great enough to
influence the degree of protection against infection provided by the vaccination. In
contrast, Petry et al (1991) found that the greater the perceived stress, irascibility,
depression, and anxiety, the greater the peak antibody response. Finally, in a recently
completed dissertation, Anna Marsland found that trait negative affect (also called
neuroticism or emotional instability) is associated with poorer antibody response to the
second vaccination. However, perceived stress (assumed to assess a state response) was not
associated with response. In a single study of antibody response to influenza
vaccinations, Kiecolt-Glaser et al. (1996) found that elderly caregivers for spouses with
a progressive dementia (hence under chronic stress) had impaired primary response to an
influenza virus vaccination when compared to matched (noncaregiver) controls.
References
Glaser, R., Kiecolt-Glaser, J. K., Bonneau, R. H., Malarkey, W.,
Kennedy, S., & Hughes, J. (1992). Stress-induced modulation of the immune response to
recombinant hepatitis B vacine. Psychosomatic Medicine, 54, 22-29.
Kiecolt-Glaser, J.K., Glaser, R., Gravenstein, S., Malarkey, W.B.,
& Sheridan, J. (1996). Chronic stress alters the immune response to influenza virus
vaccine in older adults. Proceedings of the National Academy of Sciences of the United
States of America, 93, 3043-3047.
Jabaaij. L., Grosheide, P.M., Heijtink, R.A., Duivenvoorden, H.J., Ballieux, R.E.,
& Vingerhoets, A.J.J.M. (1993). Influence of perceived psychological stress and
distress on antibody response to low dose rDNA hepatitis B vaccine. Journal of
Psychosomatic Research, 37, 361-369.
Petry, L.J., Weems, L.B., & Livingston, J.N. (1991). Relationship of stress,
distress, and the immunologic response to a recombinant hepatitis B vaccine. The Journal
of Family Practice, 32, 481-486. |