Intravenous methylprednisolone efficacy in status asthmaticus of childhood.

Forty-nine nonsteroid-dependent children hospitalized with status asthmaticus were randomized to receive IV placebo or methylprednisolone treatment (1 mg/kg every six hours). All patients received nebulized isoetharine inhalations and continuous IV aminophylline infusion. Twenty-four hours after admission, the methylprednisolone-treated patients demonstrated a greater rate of improvement in their clinical scoring index than did placebo-treated children. However, the duration of hospital stay was not significantly shortened. Twenty-eight of the patients performed serial bedside spirometry at 0, 12, 24, and 36 hours after admission. The methyl-prednisolone-treated patients experienced a more rapid recovery from peripheral airway obstruction as measured by forced expiratory flow rate during 25% to 75% of forced vital capacity (FEF25-75). The magnitude and rate of improvement in FEF25-75 was significantly greater at 36 hours (P less than .05) and independent of changes in peak expiratory flow rate, forced vital capacity, or forced expiratory volume in the first second of forced vital capacity. Placebo-treated patients had a higher incidence of asthma relapse within 4 weeks of discharge (eight v two relapses, P less than .05). Findings of this study indicate that IV corticosteroid therapy is beneficial in treating pediatric status asthmaticus.

5'-Nucleotidase activity in subjects with abnormal lymphocyte function.

5'-Nucleotidase (5'N) activity was determined in lymphocytes from patients with immunodeficiency diseases and in T-lymphocyte subpopulations from normal subjects. Cells from two patients with DiGeorge syndrome, with normal levels of B cells, and one patient with partial DiGeorge syndrome were found to have diminished 5'N activity. Utilizing monoclonal antibodies to deplete T-lymphocyte subpopulations, we found similar levels of 5'N in the cells remaining after depletion of OKT4- or OKT8-positive cells when 5'N values were determined after overnight incubation. If 5'N activity was determined on the day of the fractionation, however, OKT4-depleted cells had approximately threefold greater enzyme activity. These studies indicate that 5'N activity may vary in T lymphocyte subpopulations depending upon cell culture conditions. Diminished levels of 5'N activity are seen in patients with abnormal T-lymphocyte differentiation, as well as abnormalities of B-lymphocyte differentiation.

5'nucleotidase activity in mitogen-stimulated adult and cord blood lymphocyte cultures.

Ecto 5'Nucleotidase (5'N) activity was determined in adult and cord blood lymphocytes before and after stimulation by phytohemagglutin (PHA) and pokeweed mitogen (PWM). After 7 days of culture, the mean 5'N level +/- S.E. in unstimulated adult cells was 15.9 +/- 3.21 nm/h/10(6) cells. Cells stimulated by PHA and PWM for 7 days had 5'N levels of 44.65 +/- 6.69 nm/h/10(6) cells and 33.24 +/- 7.67 nm/h/10(6) cells, respectively. Unstimulated cord blood cells cultured for 7 days had a mean 5'N level of 3.22 +/- 0.94 nm/h/10(6) cells whereas the level in PHA-stimulated cultures was 39.50 +/- 10.52 nm/h/10(6) cells and in PWM stimulated cultures 46.01 +/- 8.93 nm/h/10(6) cells. T-cell enriched and T-cell depleted subpopulations stimulated with mitogen generally did not show as great a degree of enhancement of 5'N activity as did unfractionated cells. This study indicates that 5'N activity is enhanced in cells that have been activated by mitogen stimulation. Although unstimulated cord blood cells have lower levels of 5'N activity than adult cells they have the capability upon stimulation to express levels equal to those found in adults.

Association of 5'nucleotidase activity with immature granulocytes in the bone marrow of guinea pigs.

Bone marrow leukocytes from adult strain 2 guinea pigs were found to have appreciable levels of 5' adenosine monophosphate hydrolytic activity (105 nmole/h/10(6) cells). On the basis of substrate specificity studies, enzyme inhibition studies, and thin-layer chromatographic analysis of the reaction product, the activity is related to 5' nucleotidase (5'N). The enzyme activity was associated with the membrane-enriched particulate fraction of lysed bone marrow cells. The bone marrow cell-associated 5'N activity was consistently very high in all five strains of guinea pigs examined (77--127 nmole/h/10(6) cells) and the range of activity was at least 10-fold greater than that observed for bone marrow cells obtained from mice, rabbits or rats. Furthermore, the bone marrow cell-associated 5'N activity in strain 2 guinea pigs was 5-fold greater than that observed for spleen and at least 13-fold greater than that of blood, mesenteric lymph nodes or thymus obtained from the same animal. Fractionation of strain 2 guinea pig bone marrow cells on Percoll density gradients showed that as the proportion of immature granulocytes increased in the various cell fractions, so did the 5'N activity. The cell fraction that sedimented at a density of 1.071 g/ml had the highest 5'N activity and the majority of the cells (94%) were immature granulocytes. The bone marrow compared to blood and spleen had the highest number of total granulocytes and the highest percentage of immature granulocytes. We conclude that the elevated bone marrow-derived 5'N activity in guinea pigs is associated with the resident population of immature granulocytes in that tissue.