Squaric acid dibutylester (SADBE), a potent contact allergen, was tested for mutagenicity in the bacterial plate incorporation assay (Ames test), in the presence and absence of mammalian microsomes. In contrast to dinitrochlorobenzene which is mutagenic in this test, SADBE was found not to be mutagenic. In 53 patients with extensive or total alopecia areata, SADBE dissolved in acetone was applied weekly to one side of the head, the other side serving as control. In 46 patients (87%), hair regrew either exclusively on the treated side, or considerably faster and denser on this side. In some patients, continuous treatment failed to maintain the response. Persistent response was observed in 37 patients (70%). These results are essentially the same as those obtained with DNCB. Therefore, contact allergy is proposed as a therapeutic concept for alopecia areata.
A new method has been developed that allows in vitro differentiation of rat mast cells from precursor cells in the absence of feeder layers. In the present investigation, the precursor cells are further characterized as to their nature, state of activation and distribution in different organs of the rat. The data support our previously published evidence, based on morphology and enzyme-cytochemical reaction patterns that the precursor cells are mononuclear phagocytes. Peritoneal macrophages elicited by mineral oil, thioglycollate or proteose-peptone have lost the ability to differentiate into mast cells. Single cell suspensions of spleen and bone marrow contain mast cell precursors, while cells from mesenteric lymph nodes and thymus or purified lymphocytes never yield mast cells in this culture system.
Using serum from human atopic individuals with a sufficiently high titre of IgE and IgG antibodies to birch- or hazel-pollen allergens and antigens, the localization of IgE binding sites in birch- and hazel-pollen grains was determined by pre- and post-embedding electron microscopic immunoautoradiography with 125I-anti-IgE, whereas the IgG binding sites were localized in ultrathin sections of birch-pollen grains by the protein-A/gold technique. Concerning the distribution patterns of both IgE/IgG binding sites within the pollen grains, no difference could be observed in the dormant pollen grain: Labelling was found in the exine part of the pollen wall and throughout the highly condensed cytoplasm except for starch grains and lipid droplets. The intine part and the germination pores were almost completely unlabelled. In pollen grains which had been soaked in a hypotonic buffer for 15 min, however, IgE binding sites were predominantly localized within the intine and the germination pores. The specificity of the labelling reactions and the observed differences in the localization patterns are discussed.
The sera of 4 patients with bullous pemphigoid, of 5 patients with drug reactions and of 13 patients with atopic eczema were examined for the occurrence of low molecular weight eosinophil chemotactic factor (ECF) by fractionation on a Sephadex G 25 column. Almost all patients had a peripheral eosinophilia, and many had raised total serum IgE levels. ECF was demonstrated in the sera of all 4 patients with bullous pemphigoid and in 4 of 5 patients with systemic drug reactions. In contrast, the sera of the 13 patients with atopic eczema did not contain any ECF activity, nor did the 13 control sera. These findings suggest that the ECF from phagocytosing polymorphonuclear leukocytes (PMN) and/or the mast cell derived ECF-A contribute to the elevated serum ECF levels in patients with bullous pemphigoid and drug reactions. A correlation between serum ECF and IgE levels and peripheral eosinophilia could not be established.
Analogous reactions of grass and corn pollen extracts in skin tests on patients suffering from pollinosis might suggest an antigenic relationship between grass and corn pollens. This problem was studied using the RAST inhibition test. Tests were performed with cellulose discs labelled with commercial skin test extracts containing grass, rye, wheat, barley, oat and maize pollens. Different mutual inhibitions were measured showing various grades of antigenic relationship. Only grass pollen antigens could strongly inhibit all other antigen-antibody reactions. Thus, we suppose that the investigated grass pollen extract also contains all antigens typical of corn pollen. Therefore, exclusive use of this extract seems to be possible in diagnosis and perhaps therapy of combined grass and corn pollen allergy.
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