Effect of radiation and age on immunoglobulin levels in rhesus monkeys (Macaca mulatta).

We report the results of a study on the immunoglobulin levels of rhesus monkeys (Macaca mulatta) in a colony consisting of the survivors of monkeys that received a single whole-body exposure to protons, electrons or X rays between 1964 and 1969. This colony has been maintained to assess the long-term effects of ionizing radiation on astronauts and high-flying pilots. Of the original 358 monkeys that were retained for lifetime studies, 129 (97 irradiated and 32 controls) were available for our study. We found no significant difference between the irradiated and control monkeys in mean levels of IgA, IgG and IgM, irrespective of the radiation treatment. The availability of these aged monkeys provided a unique opportunity to compare their immunoglobulin levels to those of other monkeys of various ages, and thus assess the effect of age on immunoglobulin levels. We found that only the IgA levels increase with age.

The effect of age on the level of human ABO blood group antibodies.

It is generally assumed that cellular and humoral immunity decline in aging humans. Although there have been reports that the naturally-occurring ABO antibodies also decline with age, some of the data are incomplete and others contradictory. Our study involved only healthy women of various ages and included assays of anti-A and anti-B titers in A, B, and O subjects. Statistical analyses of the data showed that while the antibody titers decreased with age, the amount of change was very small relative to the amount of variability among individuals and the variability attributable to blood type and season of the year. Comparisons with a previous study (1) from our laboratory showed that the changes due to aging were also small relative to the variability in titer scores within an individual over the course of a year. Based on this study, we conclude that the decrease in antibody titers with age is of doubtful clinical significance.

Ontogeny of the thymus gland of a marsupial (Monodelphis domestica).

The gray short-tailed opossum (Monodelphis domestica) has recently been established as a laboratory animal; consequently, its utility as an animal model is enhanced as more of its basic biologic characteristics become defined. To this end, we studied the ontogeny of the thymus gland in M. domestica ranging in age from the day of birth to over three years. In contrast to most Australian marsupials, M. domestica possesses only a thoracic thymus. The thymus is large in neonates and remains large until young adulthood (six months of age). It has a well-defined cortex, medulla and Hassall's corpuscles. At about six months of age, the thymuses of most animals begin to atrophy, the cortex and medulla being replaced by fat. By 28 months of age, about 50% of animals have thymuses that are completely atrophied. Thus, the ontogeny of the thymus of M. domestica appears to be similar to that of eutherian mammals.

Linkage between two blood-group markers in rhesus monkeys (Macaca mulatta).

Using marker data on an extensive pedigreed population from the Wisconsin Regional Primate Research Center, we report the first genetic linkage in rhesus monkeys (Macaca mulatta). Five blood-group markers (G, I, J, K, and Q) and one serum protein marker (transferrin) were analyzed. Linkage analyses indicate the existence of loose linkage between G and Q (maximum lod score, Zmax = 4.84 at theta m = 0.314 +/- 0.38, theta f = 0.266 +/- 0.054). The genetic linkage described here constitutes the initial step toward the description of a genetic map in this species.

Blood groups in a marsupial (Monodelphis domestica).

We produced alloimmune sera against erythrocytes of the marsupial, Monodelphis domestica. By absorption fractionation, six operationally monospecific blood typing reagents (hemolysins) were prepared. Using segregation analyses, we found that each reagent detects a blood group antigen controlled by an autosomal dominant gene. With the description of these genetic markers, the utility of M. domestica as an animal model is enhanced.

A preliminary analysis of consortium data for markers tightly linked to multiple endocrine neoplasia type 2A.

We have analyzed DNA marker typing data contributed by six independent groups to estimate the pairwise genetic distances between these markers and the locus for multiple endocrine neoplasia type 2A (MEN 2A). We used LIPED to calculate these distances for female, male, and sex-average linkage maps and to determine the corresponding LOD scores. The preliminary analyses of this large data set (89 MEN 2A families and five non-MEN 2A references families, with 1,934 total individuals) are reported here. These refined estimates of the genetic map in this region will aid in the assignment of presymptomatic diagnoses. This study clearly points out the limitation of pairwise linkage analysis in further refining the position of MEN2A in this small region of chromosome 10. Further refinement of the genetic map position of MEN2A will be best accomplished by finding, verifying, and accurately mapping crossovers in specific families.