38
The Marshallese in this study showed a decreasing transformation of lymphocytes with PHA
stimulation which was well correlated with increasing age. These results indicated that the per-
centage of lymphocytes that can respond to PHA
was reduced as theMarshallese grew older. Such
a finding appearsto indicate a general decrease in
immunological capacity of the lymphocytes, assuming that the response of these cells to specific
antigensis similarly impaired.
Peripheral blood counts showed a decrease in
lymphocytes well correlated with aging and compatible with cellular depletion and reduction in
immunological capacity generally noted in the
aged.#8 These results indicate that with aging
there is on an absolute basis a greater loss of
PHA-committed lymphocytes than of non-
committed types. The slight decrease noted in the
hematocrit and platelet levels may also be part of
the phenomenonof age-related cellular depletion.
chickens was related to continuous contact with
infectious organisms resulting in hyperimmuniza-
tion. Such a situation may be present in the
Marshallese.
The increased gammaglobulin levels seem to be
incompatible with decreased immunological re-
actions in the aged. It has been suggested that the
increased globulin levels may be partly related to
the development of autoantibodies with age.
Blumenthaland Berns*’ state that“... while antibodies to exogenous antigens decrease with age
there may be an age-related increase in gamma
globulins, presumably containing antibodies to
endogenous substances.” On the other hand the
changes may be of a compensatory nature. Perhapsin older people immunoglobulins are con-
served by some mechanismswhich tend to decrease
catabolism or excretion. Orthecells still capable
of producing antibodies might be moreactive. If
it had been possible to study age-related integrity
Such reduction, however, was not noted in the
of plasmacells and other lymphatic andreticuloendothelial tissues in these people, further light
might have been shed on the problem.Finally, no
attempt was made in the studies to separate
“normal” older people from those with various
protein levels {both albumen and globulin) well
some of the age-correlated changes may be associated with morbid processes. But are not these
processes part of aging? It will be interesting in
future studies of this population to see whether
longitudinal changes on an individual basis agree
with the cross-sectional results.
Interpretation of the differences between the
exposed and unexposed populationsis difficult because radiation-induced aging is a poorly understood phenomenon.It is generally considered to
case of neutrophils. The increasing sedimentation
rate noted with aging in the Marshallese could be
related to a cumulative effect of chronic infections
and debility in the older age groups.
Electrophoretic studies of the serum showed
above the usually accepted norms for Caucasians.
This may be related in part to dehydration and
lowered blood volumes, as mentionedearlier. The
increase in gammaglobulin levels in the aging
Marshallese is consistent with many reports in the
literature.5°-53 Possibly the slightly lower albumen
levels noted in the older Marshallese mayberelated to lowered food intake.
As expected from the serum electrophoretic
data, the immunodiffusion studies showed increas-
ing immunoglobulin levels with increasing age
(Figure 37). The most pronounced and most age-
correlated change wasin the IgG group. Since the
K light chains are twice as prevalent as the L
light chains in the IgG immunoglobulins,** the
significant increase in the K light chains paralleling the increase in the IgG groupis notsurprising.
The K/L ratios in the Marshallese are similar to
those in Caucasians®* and show slight butsignificant increase in older people.
The increase in immunoglobulins in the older
Marshallese people is probably related to an accumulation of immunological reactions to infections. Parfentjev°® suggested that the increase in
gamma globulins he noted in aging dogs and
morbid changes(if that is possible). Therefore
be a late effect of radiation, a manifestation of
nonreparable injury, since aging effects are usually
not recognizable early. The relative depression of
the peripheral blood elements in the exposed
Marshallese is probably a continuing manifestation of incomplete recovery from the hematopoietic injury originally sustained. Therefore, if such
an effect is a part of the aging process, it has been
present since exposure, since continuing depression
of blood elements has been noted on annualexaminations. Thesignificant depression of the serum globulins and increase in serum albumens
in the exposed population is a notable finding.
The depression in the gammaandalphaglobulins
andparticularly in the IgA moiety andto lesser
extent in the IgG group and the L light chains