Michael E. Norman

Release of Neutrophil Chemotactic Activity during Immediate Hypersensitivity Reactions in Humans

Heat-stable, serum-derived chemotactic activity for neutrophils is shown in a human model of immunoglobulin E-mediated asthma. Twenty-six ragweed-sensitive subjects underwent bronchial provocation challenge using ragweed and Mecholyl. Increased neutrophil chemotactic activity was found in serum tested from 5 to 30 min after a positive ragweed-inhalation challenge, but not after negative ragweed challenge. The appearance of neutrophil chemotactic activity did not reflect the effects of bronchospasm alone, because it was not found after bronchospastic responses to Mecholyl in the same subjects. There were no accompanying changes of serum complement activity, nor evidence of inhibition of the chemotactic activity by proir exposure to antisera to the third and fifth components of complement. Ultrafiltration of serum showed chemotactic activity contained in fractions of at least 50 000 daltons. This appears to be the first demonstration of neutrophil chemotactic activity liberated during experimentally induced immunoglobulin E-mediated asthma in humans.

Antigen-induced neutrophil chemotactic activity in man: Correlation with bronchospasm and inhibition by disodium cromoglycate

We have previously reported increased neutrophil chemotactic activity in sera obtained after positive antigen inhalation responses in atopic subjects. This report describes the kinetics of appearance of this serum activity and the effects of antigen dose and disodium cromoglycate pretreatment on the response in 10 ragweed-sensitive subjects. Significantly increased chemotactic activity was present as early as 1 min, peaked at 10 min, and persisted through 24 hr after inhalation of antigen. The increased chemotactic activity correlated with the degree of bronchospasm induced by antigen inhalation and the amount of antigen administered. The increased chemotactic activity and bronchospasm were blocked by administration of disodium cromoglycate prior to antigen challenge. These findings are consistent with a postulated antigen-induced anaphylactic release of chemotactic activity. The correlation of this activity with the degree of bronchospasm and its appearance after administration of even small doses of antigen suggest that this activity may be important in antigen-mediated bronchospasm.

Urinary citrate excretion in the diagnosis of distal renal tubular acidosis

Since hypocitraturia in distal renal tubular acidosis, we screened the asymptomatic children in three families with familial dRTA, by comparing their 24-hour urine citrate excretion to values obtained in 45 normal children. Subsequent acid loading uncovered four new cases of dRTA suspected because of the finding of hypocitraturia. Because hypocitraturia probably contributes to nephrolithiasis/nephrocalcinosis and subsequent renal damage in dRTA, affected family members were treated with alkali (4 mEq/kg/day), which normalized urine citrate in three children; in a fourth child citrate excretion rose but was not normal. Measurement of urine citrate excretion was superior to other currently proposed screening tests for dRTA (first morning urine pH and sediment, urine concentration).

Decreased erythrocyte Na+, K+-ATPase activity associated with cellular potassium loss in extremely low birth weight infants with nonoliguric hyperkalemia

To determine whether a shift of potassium ions from the intracellular space to the extracellular space accounts, in part, for the hyperkalemia seen in extremely low birth weight infants, we examined potassium concentration in serum and erythrocytes from extremely low birth weight infants with hyperkalemia (n = 12) or with normokalemia (n = 27). In addition, to determine whether the shift of potassium was associated with low sodium-potassium-adenosinetriphosphatase (Na+,K(+)-ATPase) activity, we studied the activity of ATPase in the last 16 infants enrolled in the study. Fluid intake and output were measured during the first 3 days of life. Infants were considered to have hyperkalemia if the serum potassium concentration was 6.8 mmol/L or greater. Blood was obtained daily for intracellular sodium and potassium levels by means of lysis of erythrocytes. The remaining erythrocyte membranes were frozen and analyzed for Na+,K(+)-ATPase activity. There were significantly lower intracellular potassium/serum potassium ratios in the infants with hyperkalemia for each day of the 3-day study (p < 0.001). In the hyperkalemic group, there was lower Na+,K(+)-ATPase activity than in the infants with normokalemia (p = 0.006). Low Na+,K(+)-ATPase activity was associated with lower intracellular potassium/serum potassium ratios (p = 0.006), higher serum potassium values (p = 0.02), and lower intracellular potassium concentration (p = 0.009). The urinary data demonstrated that there was no difference in glomerulotubular balance between the two groups. We conclude that nonoliguric hyperkalemia in extremely low birth weight infants may be due, in part, to a shift of potassium from the intracellular space to the extracellular space associated with a decrease in Na+,K(+)-ATPase activity.

25-Hydroxyvitamin D3 (calcifediol) therapy of juvenile renal osteodystrophy: Beneficial effect on linear growth velocity

A prospective study of renal osteodystrophy in moderate renal insufficiency was undertaken to assess the effects of 25(OH)D3 (Calcifediol) on healing of bone lesions and improvement of linear growth. One year after entering the study, the mean group growth velocity increased into the normal range and remained there in the next two therapy years. A significant correlation existed between pretherapy and one-year therapy values of growth velocity and serum 25(OH)D3 concentration. Qualitative bone histology obtained by transilial bone biopsy was also evaluated during the course of study. Catch-up growth was not seen, but potential for such growth may exist in later years in our patients.

Histamine release and complement changes following injection of contrast media in humans.

Mechanisms responsible for allergic-like reactions following administration of radiographic contrast media (RCM) are unclear. Aortic root blood specimens were obtained sequentially in 6 subjects following injection of RCM into the pulmonary artery during cardiac catheterization. In 5 subjects, elevated plasma histamine levels (up to 80 ng/ml) occurred within minutes. Levels of C3, C4, factor B, and total hemolytic complement activity were decreased in the same specimens. No hemodynamic or clinical abnormalities were noted. These findings support the concept that RCM can liberate histamine in vivo in humans. Complement alterations may be related to localized RCM-protein interaction. It is unclear whether complement changes are related to the RCM-induced allergic mediator release.

Serum complement profiles in infants and children

The purpose of this study was to examine normal serum values for the complement components, C3, C4, and C5, and total hemolytic complement (CH50) activity in 163 healthy infants and children, in the age range from birth through 14 years. There were statistically significant relationships of C3, C4, and C5, but not CH50 with age. None of the complement components or CH50 could be differentiated by sex or race. Tolerance limits for high and low values were projected for each complement measurement for 75%, 90%, and 95% of the general population. Our data confirm the differences in complement levels between children and adults and demonstrate a wide range of values within each group, reflecting the biologic variability of complement measurements. These results emphasize the importance of establishing normal pediatric values in any laboratory that measures complement profiles in various diseases of childhood.

Further characterization and biologic activity of ragweed antigen—induced neutrophil chemotactic activity in man☆

We have previously described the appearance in serum of increased neutrophil chemotactic activity (NCA) during bronchospasm induced by inhalation of ragweed antigen in ragweed-sensitive subjects. This NCA is non-complement derived, appears within 1 min after antigen inhalation, and is not seen after methacholine-induced bronchospasm. This article describes further characterization of this chemotactic activity and correlation with in vivo leukocytosis. NCA consistently eluted in the void volume (fraction I) after Sephadex G-150 chromatography of patient serum obtained 10 min postchallenge. Fraction I contained 94% of the NCA of postchallenge whole serum. Both postchallenge whole serum and fraction I deactivated neutrophils to autologous chemoattractants and complement-derived chemotactic factors, but not serum-independent chemotactic factors. NCA was chemotactic for neither human nor guinea pig eosinophils, nor for human mononuclear cells. A significant increase of circulating neutrophils was seen only after antigen-induced bronchospasm and correlated with the increase in NCA. Thus, NCA represents another inflammatory mediator of probable mast cell origin that may explain, at least partially, the accumulation of neutrophils observed in the peripheral blood, skin, and bronchial wall after immediate hypersensitivity reactions.

A familial defect of neutrophil chemotaxis with asthma, eczema, and recurrent skin infections.

Summary: A defect in chemotaxis of peripheral blood polymorphonuclear leukocytes (PMNs) was demonstrated in both parents and three of four children in a single family afflicted with varying degrees of respiratory allergy, unusual onset of severe eczema in the first month of life, and recurrent bacterial skin infections. Of great interest was the identification of HLA-B12 at the B locus in all affected members but not in the unaffected child. The two children known since infancy to be most severely affected with eczema and recurrent infections are HLA identical and homozygous for HLA-B12. The child without eczema and infections had an intermediate cellular chemotactic defect most apparent on kinetic studies.Speculation: Recently, several familial defects of neutrophil chemotaxis have been reported in association with syndromes of recurrent bacterial infections, reaginic hypersensitivity, and/or clinical atopy. Our studies extend these observations by describing the possible genetic relationships between atopy (e.g., eczema) chemotactic defects, and the HLA system. Future studies in this field should examine the association between chemotactic defects and the HLA system, and the requirements of both atopy and chemotactic defects to produce recurrent infections.

Vitamin D Metabolite Levels in Normal Children

Vitamin D metabolite levels were measured in 174 normal children throughout the year. 25-hydroxyvitamin D3 (25(OH)D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) levels showed a seasonal variation; both levels were higher in summer than in winter (p < 0.001 for both). There was a fall in the 1,25-dihydroxyvitamin D (1,25(OH)2D) level in August and September (p < 0.001), which coincided with a rise in mean 25(OH)D3 and 24,25(OH)2D3 levels. An inverse correlation was seen between 1,25(OH)2D and 24,25(OH)2D3 levels (r = -0.233; p < 0.01). 25(OH)D3 levels increased with age only for winter values (< 3 years, 11.70 ± 3.98 ng/ml; 3-11 years, 18.38 ± 1.65 ng/ml; >11 years, 23.60 ± 4.60 ng/ml) while 1,25(OH)2D and 24,25(OH)2D3 levels did not show an age-related difference. Intake of multivitamins had an interesting effect on 25(OH)D3 and 24,25(OH)2D3 levels in the winter but not in the summer; the endogenous metabolite levels were lower in the vitamin supplemented children [25(OH)D3: 23.05 ± 7.35 versus 15.77 ± 5.51 ng/ml, p < 0.001; 24,25(OH)2D3: 2.30 ± 1.11 versus 1.66 ± 0.88 ng/ml, p < 0.05]. Children studied in the winter who were not receiving supplemental vitamins were older than those who did receive the vitamins (7.26 ± 2.64 versus 5.42 ± 3.17 years; p < 0.01). Sixteen of the children had both winter and summer measurements. Their 25(OH)D3 and 24,25(OH)2D3 levels showed the same seasonal variation as the overall group data, while their 1,25(OH)2D levels showed no consistent pattern. Our data suggest that establishing normal pediatric values for 25(OH)D3, 1,25OH)2D, and 24,25(OH)2D3 requires consideration of season, age, and supplemental vitamin D intake, and that such information be available to investigators in order to make meaningful interpretations of vitamin D metabolite levels in disease states.