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Biomedical subjects

E Atlas

Publications and source records attributed to E Atlas.

12 recordsLinked to original sources
PubMed1993

Downregulation of the anti-HLA alloimmune response by variable region-reactive (anti-idiotypic) antibodies in leukemic patients transfused with platelet concentrates.

Approximately 30% to 40% of patients with acute leukemia receiving repeated pooled random-donor platelet transfusions develop anti-HLA alloantibodies. Over time, however, serum anti-HLA concentrations decrease in approximately 50% of these patients, despite continued exposure to platelet and/or red blood cell transfusions. Using an enzyme-linked immunosorbent assay to measure serum Igs, the present study demonstrates that the sera of 67% of 82 transfused patients exhibiting a decrease in anti-HLA contain antibodies (anti-idiotypes) that react with the variable (V) region of anti-HLA antibodies. Anti-HLA binding to platelet membranes could be inhibited by these serum antibodies in 36% of the patients, indicating they had paratope-related reactivity. Protein G sepharose absorption showed that the anti-HLA V region-reactive antibodies were IgG. Of the 43 patients who had a decrease in anti-HLA levels, that were 16 whose anti-HLA decreased to undetectable levels; 7 (44%) developed anti-idiotypic antibodies that could specifically inhibit their own previously anti-HLA-positive serum. In contrast, antibodies with reactivity to the V region of anti-HLA antibodies (anti-idiotypes) were not demonstrable in patients who developed anti-HLA that did not decrease or disappear. The findings suggest that the development of anti-HLA V region-reactive antibodies (anti-idiotypic antibodies) correlates with a decrease in anti-HLA antibody formation in patients multiply transfused with platelet concentrates. The observations indicate that anti-idiotypic antibodies may downregulate alloimmune responses in patients undergoing repeated allostimulation during platelet transfusion therapy.

Acute Disease↗
PubMed1991

In vivo acquisition of Fc gamma RII expression on polyoma virus-transformed cells derived from tumors of long latency.

BALB/c 3T3 cells transformed in vitro with polyoma virus were cloned and passaged once in syngeneic mice. Resulting tumors from each clone were explanted and recultured. Expression of receptor for Fc of IgG (Fc gamma RII) in the original in vitro maintained clones and in cells derived from tumors elicited by the respective cells was measured at the protein level as well as at the mRNA level. Clones were assayed in pairs. The ancestor in vitro maintained clones [designated cultured cells (C)] were compared with cells derived from the same clones after a single passage in vivo followed by explantation and reculturing [designated cultured-tumor-cultured cells (CTC)]. C cells of any of the tested clones did not express Fc gamma RII. On the other hand, certain CTC cells were positive. The Fc gamma RII-positive cells were derived from tumors appearing after a long precancer latency period (greater than 140 days). CTC cells derived from tumors that appeared after shorter latency periods (less than 80 days) were Fc gamma RII negative. These results were obtained both by using radioimmunoassay and monoclonal antibodies against mouse Fc gamma RII as well as by Northern blot analysis using the Fc gamma RII complementary DNA probe. The involvement of macrophages as the Fc gamma RII-expressing cells in CTC cells was excluded. Fc gamma RII expression was down-regulated in CTC cells as a function of time following their explantation into culture. Fc gamma RII expression could be up-regulated in these cells and induced on C cells by maintaining the cultured cells in the presence of normal mouse serum or recombinant interferon. We also tested the expression of Fc gamma RII on CTC cells following their inoculation into syngeneic mice for a second time (CTCx2 cells). The results showed a positive correlation between Fc gamma RII expression in the inoculated ancestor CTC cells and on the CTCx2 cell progeny.

Animals↗
PubMed1983

Central nervous system toxoplasmosis in homosexual men.

Many opportunistic infections have been associated with an acquired immunodeficiency state in which cellular immune status has been altered. Two homosexual patients are described who presented with fever, peripheral eosinophilia, and a travel history to Haiti and were found to have central nervous system toxoplasmosis. Despite definitive diagnosis and appropriate therapy, both died. Techniques for diagnosis of central nervous system toxoplasmosis are discussed, and the importance of brain biopsy in this clinical situation is stressed. Eosinophilia may serve as an early diagnostic marker for disseminated toxoplasmosis in homosexual patients.

Adult↗
PubMed1978

Nosocomial respiratory tract infection and colonization with Acinetobacter calcoaceticus. Epidemiologic characteristics.

Nosocomial respiratory tract infection with Acinetobacter calcoaceticus occurs frequently in many hospitals. An outbreak of respiratory tract infections in an intensive care unit provided an opportunity to study clinical and epidemiologic characteristics of such infections. Retrospective studies demonstrated that A. calcoaceticus in sputum was significantly associated with endotracheal intubation (p = 0.03) and continuous positive pressure ventilation (p less than 0.02). After control measures had interrupted the outbreak, a prospective microbiologic investigation demonstrated that one third of the hospital personnel had transient hand colonization with multiple strains of A. calcoaceticus. Pharyngeal, vaginal and rectal carriage was rare. A pulmonary therapist with chronic dermatitis had persistent hand colonization with the epidemic strain, and he contaminated respiratory therapy equipment. Cross contamination of respiratory therapy equipment occurred while in use, but no other inanimate reservoir was demonstrated. Although previous studies have implied that the inanimate hospital environment has unique reservoirs of A. calcoaceticus, these reservoirs were not implicated in this outbreak. Human skin must be considered an important reservoir of A. calcoaceticus.

Acinetobacter↗