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Biomedical subjects

E L Morgan

Publications and source records attributed to E L Morgan.

85 records · Page 5Linked to original sources
PubMed1980

Regulation of the immune response. II. Characterization of the cell population(s) involved in the Fc fragment-induced adjuvant effect.

Fc fragments derived from human and murine Ig have been shown to possess adjuvant properties. The spleen cell population(s) affected by the Fc fragments is the T lymphocyte. That Fc fragments do not act directly on the B lymphocyte was shown by the fact that in a system where T cell help was substituted for by TRF and using TI antigens, no adjuvant effect was observed. The adjuvant signal provided by the Fc fragments is needed early in the culture period, because it was reduced by approximately 50% when delayed by 24 hr. When the addition of Fc was delayed by 72 hr, the antibody response was not significantly increased over the culture that received antigen only.

Animals↗
PubMed1979

The requirement for adherent cells in the Fc fragment-induced proliferative response of murine spleen cells.

The proliferative response of mouse B lymphocytes induced by Fc fragments was found to be dependent upon an adherent cell population. The adherent cell is esterase positive, irradiation resistant, and not susceptible to lysis by anti-thymus serum and complement. The mechanism(s) by which Fc fragments induce B-cell proliferation could be the result of the interaction of Fc with both B cells and adherent cells or with adherent cells which then release factors that trigger the B cells to proliferate. Spleen cells from the C3H/HeJ mouse were shown to be unable to respond to Fc fragments. The addition of adherent cells from either C3H/St or C3H/HeN mice to adherent cell depleted C3H/HeJ cells enabled them to respond to Fc, indicating the defect was in the adherent cell population.

Animals↗
PubMed1979

Comparison of the binding of radiolabelled human IgG and Fc fragments to murine spleen cells.

The binding properties of an IgG1 human myeloma protein, normal IgG, and the Fc and Fab fragments of each were compared in cultures of murine spleen cells. Both 125I-labelled IgG and Fc fragments bound to splenic lymphocytes, whereas Fab fragments did not bind significantly at the highest concentrations tested. On a molar basis, more Fc bound than intact IgG. According to Scatchard plot analysis, the affinity constand of IgG1 was 1.5 x 10(6) +/- 1 x 10(5) L/M and that of the Fc fragments was 7.8 x 10(5) +/- 2.6 x 10(5) L/M. Approximately 25,000 binding sites/cell were calculated for IgG1 and 102,000 for Fc. Deaggregation of the Fc preparation did not change these values, suggesting that the difference in binding of IgG and Fc did not result from Fc aggregation. Unlabelled IgG inhibited about 25% of the labelled Fc binding, whereas unlabelled Fc inhibited approximately 80% of the labelled Fc binding. IgG antigen-antibody complexes, however, inhibited 75% of the Fc binding. In the reciprocal experiment both intact IgG and Fc inhibited the binding of labelled IgG by 100%. The major cell population that bound IgG and Fc fragments in the spleen cell preparation were the B lymphocytes. Removal of macrophages did not significantly affect the binding of labelled Fc fragments. In addition, T-cell-enriched populations bound an insignificant quantity of Fc fragments.

Animals↗
PubMed1978

The requirement for the Fc portion of antibody in antigen-antibody complex-mediated suppression.

The role of the Fc portion of antibody in immune complex-induced suppression was studied in vivo and in vitro. BSA pheasant anti-BSA complexes, formed in antigen excess (Ag1Ab1), were found to suppress both responses to BSA and SRBC. When complexes were formed with F(ab')2 fragments of pheasant anti-BSA, no suppression was observed, indicating that the Fc piece was indeed essential for the induction of Ag-Ab complex-mediated suppression.

Animals↗
PubMed1978

Immunologic tolerance in the chicken. I. Isolation of two suppressive fractions from serum of chickens tolerant to bovine serum albumin.

Serum from 14-day-old chickens rendered tolerant at hatching with 1250 mg bovine serum albumin (BSA)/KBW was found to suppress an adoptive secondary response to BSA and an in vitro response to sheep red blood cells (SRBC). Chromatographic separation resulted in three fractions: I, II, and III. The suppressive activity was found to be contained in fraction I (m.w. greater than 1 X 10(6)) and fraction III (m.w. less than 2.5 X 10(4)). Analysis of fraction I by affinity chromatographic techniques revealed that it was composed of soluble BSA-antibody complexes and their removal removed the suppressive activity. Analysis of peak III revealed that the suppressive activity could only be removed by BSA and anti-Line 3 antiserum columns.

Animals↗
PubMed1977

The role of antigen-antibody complexes in mediating immunologic unresponsiveness in the chicken.

A significant suppression of an adoptive secondary response to either BSA or sheep red blood cells (SRBC) resulted when chicken spleen cells were incubated with BSA-antibody (Ab) complexes formed in antigen excess (molar ratio Ag1Ab1.1). Serum from 14-day old birds rendered unresponsive at hatching with large doses of BSA also produced suppression. In addition the in vitro response to SRBC was suppressed by the above treatment. Complexes formed at equivalence either had no effect on the subsequent responses of primed cells or produced an enhancement. The fact that both the homologous and heterologous responses were inhibited could indicate that both were suppressed via a common pathway.

Animals↗
PubMedDate not supplied

Trabecular bone mineral density in idiopathic scoliosis.

The association of idiopathic scoliosis with an osteoporotic state has been indicated previously. The present study compared the trabecular bone mineral densities of 44 adolescent idiopathic scoliotic girls with 44 age-, weight-, sex-, and race-matched controls. Their lumbar spine and femoral neck bone mineral densities were evaluated using dual-photon absorptiometry. Radiographs and scoliotic curve data were also obtained for the experimental group. The scoliotic subjects exhibited significantly lower lumbar and femoral neck bone mineral densities than the control subjects. No effect was found with respect to treatment, degree, or progression of curvature. The results of this study indicate that there is a generalized state of osteoporosis in idiopathic scoliotic girls when compared with matched controls.

Adolescent↗
PubMedDate not supplied

Association of bone mineral density and pediatric fractures.

Bone mineral density in the lumbar spine and the left femoral neck was measured for a group of 17 children, 3-14 years of age, who had sustained traumatic fractures. Children with any signs of metabolic bone disease were excluded from the study. Identical measurements were made on an age- and sex-matched control population using dual photon absorptiometry. Analysis of bone mineral measurements revealed that there were no statistically significant differences between the lumbar and femoral neck densities of the two groups. The results indicate that reduced bone density is unlikely to play a significant role in acute traumatic pediatric fractures.

Adolescent↗
PubMedDate not supplied

Trabecular bone density and menstrual function in women runners.

Osteoporosis results in decreased bone mineral mass and reduced trabecular bone density. Although its etiology remains unknown, studies have revealed differential changes in the bone mineral densities of postmenopausal women, anorexic women, and amenorrheic female athletes. Correlations have also been made between estrogen deficiency and osteoporosis in both premenopausal and postmenopausal women. In order to examine the possibility of osteopenia, a group of 36 female runners between the ages of 15 and 44 years were evaluated for bone mineral density, menstrual function, and dietary habits. Serum calcium, phosphorus, and parathyroid hormone (PTH) levels were also determined for each participant, as were complete blood counts. Using dual photon absorptiometry, all participants underwent a 20 minute scan of the lumbar spine with specificity to the L1-14 vertebrae. The 36 subjects included 19 oligomenorrheic and 17 eumenorrheic women. Results of bone density analyses revealed that the oligomenorrheic runners had significantly lower calibrated bone mineral density (CBMD) than their eumenorrheic counterparts (P less than or equal to 0.01). Likewise, the PTH levels of the oligomenorrheic runners were also significantly lower (P less than or equal to 0.01). Analysis of dietary logs revealed no significant differences between the dietary habits, the calcium intake, or the caloric intake of the two groups. The data from this study indicate that there is a relationship between reduced serum PTH levels and the oligomenorrheic state. The loss of the protective effect of estrogen in the oligomenorrheic runners possibly contributed to their reduced bone mineral densities and could be a contributing factor in osteopenia.

Adolescent↗