Platelet 3H-Serotonin Releasing Immune Complexes Induced by Pseudomonas aeruginosa in Cystic Fibrosis

In vitro formation of immune complexes was studied by ³H-serotonin release from human platelets by P. aeruginosa antigens in the presence of serum From 22 cystic fibrosis patients. chronically infected with mucoid P. aeruginosa (CF + P) and with a pronounced antibody response against these bacteria, and in 24 patients without P. aeruginosa (CF-P). All CF + P patients responded with ³H -serotonin release (16–34%), whereas CF-P patients released less than 15%. In the group of CF4-P patients the number of P. aeruginosa precipitins was correlated to the serotonin liter. Time courses indicated that SH-serotonin release was maximal between 2 and 5 min, and that no further release was observed up to 20 min. There was a gradual increase in ³H -serotonin release with higher platelet concentrations The response was not changed by complement inactivation. and fractionation of serum demonstrated that the serotonin release was dependent on the presence of the immuno-globulin fraction. These experiments support the suggestion of a type 111 reaction being invoked in the lung damage in CF + P patients and also suggest a possible involvement of serotonin in the inflammatory reaction during chronic P. aeruginosa lung infection.     

Type I reactions directed against Pneumocystis carinii in AIDS patients

Type I allergy directed against Pneumocystis carinii (PC) has been investigated in 14 patients with AIDS. The Pneumocystis carinii pneumonia often shows a rapid and severe course, and type I allergy against the parasite might be a pathogenic co-factor in the interstitial lung inflammation. In twelve of the AIDS patients the clinical symptoms and course of illness indicated a PC pneumonia. The basophil histamine release test was used as a sensitive test to detect type I allergy against PC. Eight of the patients showed significant histamine release when stimulated with PC. In contrast, only two patients in the group of 12 HIV antibody-positive homosexual men and none in the control group of 13 heterosexual men released histamine. The histamine release was mediated by an immunological reaction, since the release was abolished and regained by removal from and refixation to the cell surface of the cell-bound immunoglobulins before the antigen challenge. The results suggest an involvement of type I allergy as a pathogenic co-factor in Pneumocystis carinii pneumonia.     

Increased numbers of circulating basophils with decreased releasability after administration of rhG-CSF to allergic patients

Preliminary studies in hematological patients have indicated that treatment with rhG-CSF reduces basophil releasabilityex vivo. We examined this phenomenon further, in allergic patients. Ten patients with grass pollen rhinoconjunctivitis were given rhG-CSF (5 μg/kg/day s.c.) for 5 days, and examined before and after treatment. Basophil counts increased from 5 to 19×10⁹/l (P<0.01). Total blood histamine increased from 80 to 160 μg/l (P<0.01), corresponding to a decrease in average basophil histamine content from 1.5 to 0.81 pg/cell (P<0.01). Isolated mononuclear cells showed a significantly decreased histamine release (HR) when stimulated with A23187 and grass. Whole blood experiments showed a similar decreased HR to grass and anti-IgE (P<0.01). However, we found an increase in total blood histamine. We conclude that treatment with rhG-CSF (1) increases the number of circulating blood basophils, (2) reduces the average histamine content per basophil, and (3) reduces the basophil releasability. These findings could be due to the mobilization of immature basophils from the bone marrow.     

High Serum Beta-2-Microglobulin Levels and Circulating Immune Complexes Containing βm AND Anti-βm Antibodies in Felty's Syndrome

Serum beta-2-microglobulin (β₂m) levels, incidence and levels of anti-β₂m autoantibodies, and quantity of circulating macromolecular complexes containing β₂m were studied in patients with Felty's syndrome (FS), joint-restricted rheumatoid arthritis (RA), and healthy controls. The serum β₂m concentrations detected in the FS group (6.95 ± 2.9 mg/liter) greatly exceeded those of the RA group (3.4 ± 1.2 mg/liter) and the control group (1.42 ± 0.69 mg/liter). Autoantibodies to β₂m were frequent in the FS group. Circulating complexes containing β₂m, prepared by precipitation in 3% polyethylene glycol, were detected in 65% of FS and 35% of RA patients. In the majority of these cases the solid-phase Clq purified immune complexes also contained βm. Detection of anti-β₂m antibodies in a significant part of complexes containing β₂m suggests the presence of specific immune complexes in this fraction of FS and RA patients.