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Biomedical subjects

O Haferkamp

Publications and source records attributed to O Haferkamp.

At least 109 records · Page 6Linked to original sources
PubMed1975

Animal experimental studies on chronic granulomatous inflammation and T-lymphocyte-system.

The presence of lymphocytes in chronic granulomatous inflammations is frequently thought to indicate that thymus-dependent cellular immune mechanisms are involved in the pathogenesis of such processes. Therefore, in the present studies, a model of a granulomatous heaptitis (induced by heat-inactivated group A streptococci) was used to determine whether liver granulomata, consisting of macrophages and lymphocytes, could also be evoked in neonatally thymectomized or in congenitally thymus-deficient nude mice. The morphological (light and electron microscopical, immunohistological) investigations were supplemented with selective determination of T- and B-lymphocyte function. The thymus-deficient mice, after injection of streptococci, developed liver granulomata that did differ neither quanlitatively nor quantitatively from those of control animals with thymus. Lymphocytes were found within the granulomata in both animal groups. There was no evidence for functional disorder of the RES in thymus-deficient mice; on the contrary, RES-activity seemed to be increased. Phagocytosis of streptococci, their intracellular breakdown and streptococcal antigen-degradation occurred as fast or faster in such animals. PHA- and LPS-stimulation of spleen lymphocytes indicated a considerable depletion of T-cells in neonatally thymectomized mice and a complete absence of T-cells in congenitally thymus-deficient nude mice. However, radioimmunological determination of antibodies to group A streptococcal carbohydrate revealed that both groups of experimental animals possessed functionally active B-cells. Therefore, the granulomatous hepatitis described here can be defined as a focal reaction of the liver RES with "B-lymphocyte trapping". Cellular immune mechanisms are not involved in the pathogenesis of these lesions.

Animals↗
PubMed1975

Antibodies to peptidoglycan in the sera from population surveys.

A recently described latex agglutination test was used to determine peptidoglycan antibody titers in sera from healthy human subjects and in sera from patients with a history of streptococcal infections or rheumatoid arthritis. Using latex particles coated with group A streptococcal peptidoglycan 32.8% of the sera from 961 healthy donors reacted positively with titers ranging from 1 : 5 to 1 : 320. Peptidoglycan antibodies were more frequently present in the younger population (45.1% in the 20-29 years old) and considerably decreased in advanced age (15.7% in the 70 years or older). Sera from 82 patients with elevated ASO-titers showed detectable peptidoglycan antibody levels in 40.2%; a statistically significant correlation between ASO and peptidoglycan antibody titers could not be substantiated. Sera from 25 patients with rheumatoid arthritis gave a high incidence (56-92%) of positive results. However there was evidence that this may be due to the action of rheumatoid factor present in such sera.

Adolescent↗
PubMed1975

Use of limulus assay to compare the biological activity of peptidoglycan and endotoxin.

The gelation of a lysate prepared from the amebocytes of Limulus polyphemus, the horseshoe crab, has been used to detect endotoxin-like material in clinical studies and in "in vitro" experiments. The investigation of blood samples from 54 hospitalized patients suspected of having endotoxemia, revealed a positive limulus test in 14. Infections due to gram-positive organisms were not associated with positive assays. These results were in agreement with the observation that living gram-positive microorganisms - in contrast to gram-negative bacteria - did not initiate lysate gelation when studied "in vitro". Only very high concentrations of peptidoglycan, isolated from the cell walls of various gram-positive bacteria, induced the reaction. Therefore, these findings support the view, that the limulus test is relatively specific for the detection of gram-negative bacterial endotoxin and endotoxemia.

Animals↗
PubMed1975

Migration inhibition of peritoneal macrophages by peptidoglycan.

Previous studies have shown that peptidoglycans from group A and B streptococci inhibit the migration of peritoneal exudate cells from non-sensitized rats and guinea pigs. In the present studies peptidoglycans from S. aureus and S. epidermidis were found to inhibit the migration of cells to the same extent as group A streptococcal peptidoglycan. In contrast, HSA-pentapeptide, an immunologically active synthetic analog of the peptide moiety of peptidoglycan which is free of the intrinsic toxicity of naturally occurring peptidoglycans, did not induce migration inhibition of peritoneal exudate cells from non-sensitized guinea pigs. Sensitization of animals with 200 mug HSA-pentapeptide emulsified in incomplete Freund's adjuvant significantly reduced the inhibitory effect of streptococcal and staphylococcal peptidoglycan; HSA-pentapeptide again showed no activity. However, when HSA-pentapeptide was tested against cells from animals sensitized with 200 mug HSA-pentapeptide incorporated in complete Freund's adjuvant, a strong inhibition of migration was evident. Skin tests performed in these animals, in contrast to the dermonecrotic reaction elicited by streptococcal or staphylococcal peptidoglycan, revealed a characteristic delay hypersensitivity to HSA-pentapeptide.

Animals↗
PubMed1975

Adjuvancy of streptococcal nucleic acids.

A study was performed to find out whether or not RNA and DNA isolated from Group A streptococcal cytoplasm does possess adjuvant activity. The findings obtained indicate that the adjuvancy of streptococcal RNA is very similar to that of poly I:C. The adjuvant activity of poly I:C is characterized by its capacity to increase the number of pre-existing hemolysin-producing spleen cells and by its ability to increase the development of 19S and 7S producers early in the 12-day-period of primary immune response. The adjuvancy of streptococcal DNA was considerably less pronounced than that of RNA. Neither poly I:C nor streptococcal RNA and DNA were found to be capable of increasing the process of priming for the secondary immune response.

Adjuvants, Immunologic↗
PubMed1974

Investigations on the specificity of the Limulus test for the detection of endotoxin.

Lysates obtained from amoebocytes of Limulus polyphemus, the horseshoe crab, showed gel formation after the addition of bacterial endotoxin. In contrast to living gram-negative bacteria, viable gram-positive microorganisms did not cause gelation of lysate. Nevertheless, peptidoglycan isolated from the cell walls of various gram-positive organisms did induce the reaction. However, the activity of peptidoglycan was 1,000 to 400,000 times less than that of Escherichia coli lipopolysaccharide. After exposure to lysozyme, peptidoglycan no longer gelled amoebocyte lysate, therefore apparently excluding endotoxin contamination. Gelation of amoebocyte lysate by endotoxin or peptidoglycan was inhibited by different concentrations of sodium polystyrolsulfonate. Whereas these studies confirm the specificity of the Limulus test for bacterial endotoxins, they also indicate that other substances of bacterial origin should be investigated for their ability to gel amoebocyte lysate.

Arachnida↗
PubMed1973

Inhibition of macrophage migration by nucleotide-containing streptococcal preparations.

Certain extracts of streptococcal cell walls are known to inhibit macrophage migration in vitro. In this study, we attempted to identify the streptococcal components responsible for this phenomenon. Trypsinized cell walls and cytoplasm from groups A and B streptococci were extracted with hot formamide followed by acetone precipitation. Subsequent gel filtration in aqueous solutions yielded a fraction devoid of C-carbohydrate and containing mostly oligonucleotides, apparently derived from streptococcal cytoplasm. This fraction significantly inhibited the migration of peritoneal exudate cells from rats sensitized to groups A and B streptococci. It was noteworthy that no inhibition of migration was observed with cells from nonsensitized animals or control rats injected with BCG or complete Freund adjuvant. Similarly, no inhibition was obtained with formamide extracts of calf thymus RNA. Although the inhibition does not show specificity for streptococcal groups, it seems to have immunological specificity since prior sensitization with streptococci is required for migration inhibition.

Animals↗