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S Jackson

Publications and source records attributed to S Jackson.

At least 289 records · Page 16Linked to original sources
PubMed1988

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Community Health Services↗
PubMed1987

Normal human sera contain antibodies directed at Fab of IgA.

Serum samples from 26 normal volunteers were evaluated by isotype-specific ELISA for the presence of IgG and IgM antibodies directed at IgA. Although there were wide variations in antibody levels, anti-IgA antibodies of both isotypes were found in all individuals tested. The anti-IgA activity was detected against a variety of polymeric and monomeric IgA1 and IgA2 myeloma proteins containing both kappa and lambda light chains. By using Fab and Fc fragments generated by incubation of an IgA1 myeloma protein with IgA1 protease, it was shown that the anti-IgA activity was specific for the Fab portion of the IgA molecule. It was also demonstrated that the serum of two individuals contained both IgG and IgM activity directed at autologous affinity-purified IgA. IgM antibody levels against both whole IgA and Fab of IgA were significantly higher than IgG antibody levels. Cells producing anti-IgA antibodies of both isotypes were detected in lipopolysaccharide-stimulated human spleen.

Antibodies, Anti-Idiotypic↗
PubMed1987

Aberrant synthesis of antibodies directed at the Fab fragment of IgA in patients with IgA nephropathies.

The sera of 37 patients with IgA nephropathy (IgA NP) were assayed for levels of antibodies specific for the Fab fragment of homologous IgA, and the values obtained were compared to antibody levels in a panel of 26 normal volunteers. IgG antibody levels in IgA NP patients were significantly elevated over those of the controls (P less than 0.01); at the same time IgM anti-Fab alpha levels were significantly decreased when compared to the control panel (P less than 0.01). There was no correlation of antibody levels of either isotype with levels of circulating immune complexes; however, IgM antibody levels of IgA NP patients showed a significant negative correlation with severity of renal insufficiency.

Adolescent↗
PubMed1987

Striking elevation of serum IgA, IgA-containing immune complexes, and IgA rheumatoid factor in clinically silent dermatitis herpetiformis.

We describe a patient with dermatitis herpetiformis with immunoglobulin A (IgA)-containing circulating immune complexes and IgA rheumatoid factor who presented with acute renal insufficiency; a renal biopsy specimen showed IgA nephropathy. The renal function and proteinuria spontaneously returned to normal despite markedly elevated levels of IgA-containing circulating immune complexes, IgA rheumatoid factor, and IgA antibodies to some environmental antigens. IgA1 was the predominant subclass. IgA2-containing immune complexes and IgM rheumatoid factor were not detected. Cultures of peripheral blood mononuclear cells produced increased quantities of IgA and IgA rheumatoid factor spontaneously and after pokeweed mitogen stimulation. These data indicate that renal function can improve and remain normal despite the presence of increased levels of IgA-containing circulating immune complexes and IgA rheumatoid factor.

Acute Kidney Injury↗
PubMed1987

IgA antibody-producing cells in peripheral blood after antigen ingestion: evidence for a common mucosal immune system in humans.

The finding that ingestion of antigens results in the selection induction of IgA antibodies in external secretions suggests that antigen sensitizes Peyer's patch lymphoid cells, which migrate to mucosal sites and generate local secretory IgA (S-IgA) antibody responses. Evidence for a common mucosal immune system in humans has been scanty because of the difficulty in demonstrating migratory behavior of Peyer's patch cells. In the present study, peripheral blood mononuclear cells (PBMC) from human volunteers who had ingested capsules containing killed Streptococcus mutans were assayed for spontaneous antibody-producing cells. Four of five volunteers exhibited circulating IgA-producing cells within 7 days and reached maximum responses by days 10-12. One IgA-deficient subject exhibited IgM responses with identical kinetics. Pokeweed-mitogen-stimulated PBMC produced anti-S. mutans antibodies predominantly of the IgA isotype. Significant S-IgA anti-S. mutans antibodies were detected in saliva and tears by day 14, and the antibodies reached maximum titers by 3 weeks. No changes in serum anti-S. mutans antibodies were noted. The IgA-deficient subject produced salivary secretory IgM antibodies. These results suggest that, after antigen ingestion, peripheral blood contains antigen-specific precursors of IgA plasma cells and that their presence precedes the appearance of S-IgA antibodies in external secretions. Therefore, these experiments provide further support for the existence of a common mucosal immune system in humans.

Adult↗
PubMed1987

Antispermatogenic effects of cyclophosphamide in the Syrian hamster.

Cyclophosphamide is an alkylating antineoplastic drug and has been shown to impair spermatogenesis after chronic exposures. The purpose of this investigation was to determine the effect of cyclophosphamide on sperm production in hamsters following subacute intraperitoneal (ip) exposures. The Syrian hamster, Mesocricetus auratus, aged 10-11 wk, received single daily ip doses for 4 d ranging from 10 to 250 mg cyclophosphamide/kg body weight. Control hamsters received an equivalent volume of phosphate-buffered saline solution. Testis weight, caudal sperm number, and sperm morphology were monitored for 12 wk. Cyclophosphamide failed to induce sperm abnormalities. Testis weight and sperm count were slightly suppressed at wk 1 and 4 before returning to normal at wk 12. This study showed that subacute doses of cyclophosphamide in hamsters did not significantly affect the sperm production as previously reported in other animals.

Animals↗
PubMed1987

Induction and molecular properties of secretory and serum IgA antibodies specific for environmental antigens.

A generalized secretory IgA response can be induced by ingestion of various antigens due to dissemination of sensitized precursors of IgA plasma cells from gut-associated lymphoid tissue to various secretory glands. Oral ingestion of a bacterial antigen by volunteers led to the parallel appearance of secretory IgA antibodies in several external secretions that was preceded by a transitory detection of IgA antibody-secreting cells in the peripheral blood. Naturally occurring secretory and serum IgA antibodies as well as secretory and serum antibodies induced by mucosal immunization belong predominantly to the IgA1 subclass; however, in external secretions IgA2 is the predominant subclass of natural antibodies to endotoxin and lipoteichoic acid. Although in external secretions specific IgA antibodies are of polymeric form, serum IgA antibodies to different antigens display considerable variability with respect to their distribution in polymeric and monomeric forms. However, after experimental infection, serum IgA antibodies to the influenza virus hemagglutinin are almost exclusively polymeric.

Administration, Oral↗
PubMed1986

VHDJH formation and DJH replacement during pre-B differentiation: non-random usage of gene segments.

The Abelson murine leukemia virus (A-MuLV) transformed cell line 300-19 was derived from the bone marrow of an adult NIH/Swiss outbred mouse. The original 300-19 clonal isolate carried DHH rearrangements of both JH alleles, a molecular genotype characteristic of early pre-B cells. During propagation in culture, the 300-19 line frequently generates secondary rearrangements of its JH alleles including rearrangements which append VH segments to the pre-existing DJH complexes to form complete VHDJH variable region genes and secondary D to JH rearrangements which replace the pre-existing DJH rearrangement by joining an upstream D to a downstream JH. The two types of secondary rearrangement events occur at approximately equal frequency. Approximately 30% of the VH to DJH joins lead to the production of mu heavy chains providing support for a regulated model of allelic exclusion. Like pre-B cell lines from other origins, the 300-19 line preferentially utilized VH gene segments from the more JH-proximal (3') families to form VHDJH rearrangements. However, the VH segments preferentially employed by 300-19 were from a different family than those previously demonstrated to be utilized by pre-B lines of BALB/c origin; we relate these different utilization patterns to differences in the organization of the more 3' VH families between the two strains. The initial DJH rearrangements of the 300-19 line employed more 3' (JH-proximal) D segments; however, the DJH replacements preferentially employed the most 5' D segment. We discuss this phenomenon in the context of a mechanism which may target recombinase to regions of the chromosome more 5' to the D locus (VH-containing regions) once an initial DJH complex is formed.

Abelson murine leukemia virus↗
PubMed1986

The human IgA system: a reassessment.

In healthy adults the total daily production of secretory and serum IgA exceeds that of other immunoglobulin classes. Secretory and serum IgA display features of mutual independence: they are represented by molecules with different physiochemical and immunochemical properties and antibody activities and are produced by cells with different organ distributions. Secretory and serum IgA also exhibit different effector functions: interaction of secretory IgA with environmental antigens results in prevention of the penetration of such antigens by a variety of mechanisms. Although the function of polymeric serum IgA antibodies in certain animal species involves elimination of antigenic substances by noninflammatory means, the primary function of serum IgA remains unknown. It is proposed that in humans monomeric serum IgA (which prevents activation of the complement systems, inhibits phagocytosis and antibody-dependent cellular cytotoxicity) may protect endogenous antigens expressed on various cells and tissues by preventing their interaction with humoral and cellular immune mechanisms that may lead to tissue damage.

Antibody Specificity↗
PubMed1986

Circulating immune complexes and immunoglobulin A rheumatoid factor in patients with mesangial immunoglobulin A nephropathies.

Circulating immune complexes (CIC) containing IgA and C3 were elevated in 48% of IgA nephropathy patients; IgA1 was the predominant subclass. IgA1-IgG CIC were detected in 44%, IgA2-IgG CIC in 7%, and IgM-IgA1 CIC in 16% of the patients. No IgM-IgA2 CIC were detectable. Sucrose gradient ultracentrifugation indicated that IgG-IgA1 CIC were predominantly of intermediate (13-19S) size whereas IgA1-C3 CIC sedimented from 11S to 19S. At acid pH, isolated CIC revealed the presence of substantial amounts of 7S IgA. One third of the patients had elevated serum IgA rheumatoid factor (RF) of both polymeric and monomeric forms despite normal levels of IgM-RF; 87% of patients with elevated IgA-RF had IgA1-IgG CIC. These results indicate that the IgA1 component of CIC in patients with IgA nephropathy is not necessarily of mucosal origin and suggest that a portion of these CIC consists of IgA RF immunologically complexed with autologous IgG.

Antigen-Antibody Complex↗
PubMed1986

Dopamine inhibits the aldosterone response to upright posture.

Aldosterone secretion in man is stimulated by potassium, ACTH, and angiotensin II and is inhibited by dopamine (DA). In normal sodium-replete supine individuals, aldosterone secretion is under maximum tonic inhibition by DA. Dopaminergic control of aldosterone secretion is modified by dietary sodium depletion. To determine the physiological significance of dopaminergic inhibition of aldosterone secretion, we studied the effect of DA on the aldosterone response to upright posture. Twelve normal men were studied while eating an ad libitum sodium diet, and the effect of DA was determined in the supine and upright positions. Plasma aldosterone (PAC), plasma cortisol (F), plasma aldosterone-stimulating factor (ASF), PRA, and blood pressure were measured while the men were supine and after 4 h of upright posture during an infusion of 5% dextrose vehicle and during a DA infusion of 4.0 micrograms/kg X min. The men also were studied as a time control in the supine position while receiving vehicle or DA. PAC increased from a mean basal value of 20.4 +/- 3.2 ng/dl (+/- SE) by 25.9 +/- 5.1 ng/dl to a peak of 44.4 +/- 2.4 ng/dl in response to upright posture during vehicle infusion. The PAC response to upright posture was reduced to 7.4 +/- 1.8 ng/dl (P less than 0.05) when DA was infused. The increase in PRA with upright posture was 3.7 +/- 1.3 ng/ml X h during the vehicle infusion and 4.1 +/- 1.1 ng/ml X h (P = NS) during the DA infusion. ASF, F, and blood pressure were not altered by upright posture and DA. PAC did not change in the six men infused with DA while supine. Therefore, DA inhibits upright aldosterone responses without affecting PRA, ASF, or F.

Adult↗