Age-related changes in T- and B-lymphocyte subpopulations in the peripheral blood.

Quantitation of T and B lymphocytes in infants and children is an important test in the diagnosis of a suspected immuno-deficiency. Previous studies indicated that the absolute and relative numbers of lymphocyte subpopulations vary with age, but these data in the pediatric age group are incomplete and often contradictory. We reviewed the literature and investigated the relationship between age and lymphocyte subpopulations in healthy infants and children using common methods and recent methodologic improvements. We found that absolute numbers of T and B cells followed the same trend as the total lymphocyte count, which was elevated at birth, increased in the first six months, and then gradually decreased to adult levels at approximately 13 years of age. Compared with adult values, the percentage of B cells also was higher at birth and continued to increase for six months, followed by a gradual decrease to adult levels by late childhood or early adolescence. The percentage of T cells gradually increased to adult levels by the same age range.

Age-related changes in mitogen-induced lymphocyte function from birth to old age.

This study examines the relationship between age and mitogen-induced lymphocyte blastogenesis. Lymphocytes were stimulated with PHA; Concanavalin A (Con A), and PWM in 156 normal, healthy subjects ranging in age from birth to 75 years. The findings indicate a gradual but significant decrease in PHA- and Con A-induced blastogenesis with increasing age. The decrease in Con A and PHA induced in vitro lymphocyte function begins in early childhood and young adulthood, respectively, and continues throughout the age range studied. In addition, there appears to be a decreased range of lymphocyte functional capacity among the 50-75-year-old subjects. The clinical and laboratory implications of these observations are discussed.

Perivascular myofibroblasts and microvascular occlusion in hypertrophic scars and keloids.

Microvessels in normal skin, granulation tissue, hypertrophic scar, keloid, and mature scar from human subjects were studied by transmission electron microscopy. Comparative observations suggested that most microvessels in hypertrophic scar and keloid are occluded or partially occluded, apparently owing to an excess of endothelial cells. Endothelial cell contraction was also supported by the observations, and perivascular satellite cells (pericytes), some of which were identified as myofibroblasts, were observed in hypertrophic scars and keloids. Among findings from statistical analyses were that 1) the patency of microvessels in hypertrophic scar and granulation tissue is similar, as is that of microvessels in keloid and mature scar, but the patency of all these microvessels is significantly less than that of microvessels in normal skin, and 2) endothelial cell density is greater in nonpatent vessels than in patent vessels. The observed extent of microvascular occlusion supports a previously published theory that hypoxia is involved in the generation of hypertrophic scar.

The effect of lymphocyte recovery on lymphocyte typing results.

This study examines the relationship between percent recovery of lymphocytes and T- and B-cell typing results. Lymphocytes were recovered from heparinized whole blood by density gradient centrifugation. T- and B-cells were enumerated by spontaneous sheep rosetting and direct fluorescent antibody staining for surface immunoglobulin, respectively. The findings indicate that at low recovery levels ( less than 80%) there is a significant increase in variability of lymphocyte typing results and a significant increase in IgG-bearing B-lymphocytes. Possible explanations for these findings are discussed. These results suggest that lymphocyte typing results should be interpreted in relation to recovery level and that recovery levels of greater than or equal to 80% are desirable.

Prevalence of mastoid infection in prehistoric Arizona Indians.

In view of th reported high prevalence of otitis media and mastoiditis in the present-day Indian inhabitants or Arizona, when an opportunity arose to examine the skulls of prehistoric Indians in the collection of the Arizona State Museum, University of Arizona, Tucson, Arizona, it was thought that determining the prevalence of mastoiditis in them might be helpful in the treatment and prevention of mastoid infections in the present-day population. Our findings are compared with those of two other studies of mastoiditis in prehistoric Indians in another area of the United States.

Thoracic kyphosis: range in normal subjects.

Thoracic kyphosis was measured on chest radiographs of 316 "normal" subjects by means of a modification of the Cobb technique for measuring scoliosis. Patients were accepted as "normal" if they had no thoracic or spinal complaints or radiographic abnormalities in the chest including the thoracic spine. A total of 159 males and 157 female subjects 2-77 years old was studied. The relation among age, gender, and kyphosis were determined using least squares fits of first-order linear mathematical models. These results were also used to determine the expected ranges of kyphosis for a "normal" patient of a given age and gender. The degree of kyphosis increased with age and the rate of increase was higher in females than in males. Clinical explanations for this differential increase are discussed.

Immunochemical determination of human immunoglobulins: use of kinetic turbidimetry and a 36-place centrifugal analyzer.

We describe the measurement of human immunoglobulins IgG, IgA, and IgM in diluted sera, with diluted commercial monospecific antisera, with use of a 36-place centrifugal analyzer (RotoChem IIa; American Instrument Co., Silver Spring, MD 20920). The assay involves a two-point kinetic turbidimetric technique. The changes in absorbance at 340 nm between 10 and 255 s are taken for standard curve construction with use of a computer-generated cubic least-squares fit. Patients' samples are quickly calculated from the stored curve. Multiple time-interval readings are taken to observe the reaction kinetics. The lowest detectable concentrations are: IgG, 5 mg/L; IgA, 20 mg/L; and IgM, 20 mg/L. Correlation with radial immunodiffusion was excellent. Precision, accuracy, linearity, and sensitivity were very acceptable. Antigen or antibody excess can be easily detected. The accuracy of the proposed method when measuring idiotypic monoclonal proteins is greater than radial immunodiffusion. Up to 30 patients' samples can be analyzed at one time, and calculation of test results by use of the computer program is efficient and rapid.

Evaluation of a new multichannel analyzer, "Astra-8".

We evaluated a new multiple-channel chemistry analyzer, the Beckman "Astra-8," which is controlled by a microprocessor with 52K bytes of memory. The instrument we tested performed the following tests: Na, K, CO2, chloride, urea nitrogen, glucose, and creatinine. We compared the Astra-8 to a continuous-flow (SMA 6/60) and a discrete (Du Pont aca, urea nitrogen only) analyzer. The Astra-8 demonstrated excellent precision, linearity, accuracy, analytical recovery, lack of interference, ease of operation, and satisfactory comparison to values obtained by the comparison methods.