Search

Background:: The weed Parietaria judaica is one of the most important pollen allergen sources in the Mediterranean area. Objective:: We sought to identify P judaica pollen allergen, which might be used to serologically distinguish genuine Parietaria sensitization and cross-reactivity to allergens from other weed species (eg, mugwort and ragweed). Methods:: The allergen profile of P judaica IgE-reactive sera from weed pollen-sensitized allergic individuals from the Mediterranean region (n=36) with high Parietaria pollen exposure and from weed pollen-allergic patients with little or no Parietaria exposure (Austria, n=42; Scandinavia, n=8; United States, n=19) was established by CAP FEIA measurements and by IgE immunoblot inhibition experiments with recombinant allergens. Results:: The majority (83%) of the Mediterranean weed pollen-allergic patients mounted high IgE antibody levels (mean specific IgE, 20.89 kUA/L) against recombinant (r) Par j 2, whereas only 7% of the non-Mediterranean weed-allergic patients showed low IgE reactivity to rPar j 2 (mean specific IgE, 1.03 kUA/L). The cytoskeletal protein profilin and a 2-EF-hand calcium-binding allergen were identified as cross-reactive Parietaria allergens, which were recognized preferentially by Parietaria-positive, non-Mediterranean weed pollen-allergic patients. Conclusion:: rPar j 2 might be used as a diagnostic marker allergen to identify weed pollen-allergic patients who are genuinely sensitized against Parietaria pollen and thus would be particularly suited for specific immunotherapy with Parietaria pollen extract.

The relationship between maternal hormones and factors secreted by the implanting embryo is still controversial. We have analysed the in-vitro effect of oestradiol and human embryo-derived histamine-releasing factor (EHRF) on histamine release from rat uterine mast cells. Rat uterine mast cells which were preincubated with oestradiol and then challenged with human EHRF gave histamine release values two- to threefold higher than those without preincubation. The enhancement observed was time- and temperature-dependent. A similar enhancement was obtained with human sensitized basophils but not with rat peritoneal mast cells. Oestradiol, used as a direct challenge, did not induce any histamine release from either rat uterine or peritoneal mast cells, or from human sensitized basophils. Oestradiol preincubation also enhanced the histamine release induced by anti-IgE but did not enhance the histamine release induced by substance P or compound 48/80, two secretagogues that are not mediated by IgE. Moreover, uterine fragments derived from rats at various oestrus phases, with different amounts of endogenous oestrogen, were challenged in vitro with EHRF. The release of histamine by mast cells was higher at the proestrus and preimplantation phases than at dioestrus. All these findings suggest that the interaction of oestradiol with rat uterine mast cells was capable of enhancing in vitro the histamine releasing effect of EHRF.

A 659 bp cDNA clone1coding for an allergen of Pj pollen has been isolated from a lambda gt11 library, and its DNA sequence determined. The cDNA insert showed an open reading frame of 429 bp coding for an allergenic protein of 14,866 Da and a deduced amino acid sequence containing 143 residues. The expressed recombinant protein represented the major allergen Par jI since it reacted with 95% of the sera from Pj‐allergic patients (n= 22) and with two Par jI‐specific monoclonal antibodies. No similarity with other known DNA and protein sequences has been detected.

The interaction between human early pregnancy factor (EPF) and a specific receptor present on human peripheral blood mononuclear cells (PMBC) has been assessed. EPF was radioiodiated by the lactoperoxidase method to a high specific activity, and the [125I]EPF obtained bound in a specific and saturable manner to the receptors on PBMC. Saturation of the binding sites occurred at 10(-9) M. There were 6600 specific binding sites per cell in cells partially purified from pregnant women and fewer in those from non-pregnant women. Unlabelled EPF was capable of competing for binding sites with [125I]EPF, while the binding of [125I]EPF was not inhibited by human chorionic gonadotrophin. A new assay was used that permits the culture of PBMC and the detection of the surface IgG expression in the same microplate. With this method the influence in vitro of human EPF on lymphocyte expression was tested. The results demonstrated a specific inhibition of surface IgG expression of PBMC using a very low concentration of EPF (10 pg/ml).

In-vitro fertilization (IVF) of human oocytes in our laboratories gave a percentage pregnancy rate per transfer close to 20% during 1985. Embryos were grown until the two-four cell stage and then transferred to the maternal uterus. The media from these embryo cultures were collected and subjected to chromatography on heparin-Sepharose affinity columns. The bound protein fraction contained a factor capable of inducing histamine release from sensitized basophils. The effect of this embryo-derived histamine-releasing factor (EHRF) was to induce a maximum 56 +/- 7% release of the total histamine available. This value varied between 20 and 60%, resulting from 10-30 micrograms/ml of EHRF. Since the histamine release assay performed with basophils from non-atopic donors gave no positive results, we conclude that the release was not due to a cytotoxic mechanism. This was also supported by the absence of histamine release when the assay was performed at 0 degree C, or in the presence of 2 mM EDTA, suggesting that release was dependent on an immunological interaction between EHRF and some receptor on the basophils. The immunosuppressive role of histamine is well known, and a model involving EHRF and histamine is suggested here to explain the mechanism mounted by the embryo to escape maternal immune rejection.

In this paper are presented preliminary results on the identification of a histamine-releasing factor. This factor was partially purified by means of affinity heparin-Sepharose chromatography from media in which 2-cell human embryos were cultured. The culture was performed in preparation for an in-vitro fertilization (IVF) programme. The mean value of histamine release evoked by the embryo-derived histamine-releasing factor (EHRF) was 56.7%. The release was not due to cytotoxicity since no histamine release was obtained with unsensitized cells and when the assay was performed at 4 degrees C. As a control, no histamine release was obtained using medium from unfertilized oocytes or medium alone. The EHRF could be one of the first signals from the embryo to the uterus. The immunosuppressive activity of histamine is well known, and we suggest that the local secretion of histamine in vivo by uterine mast cells, alone or in cooperation with other factors and/or mechanisms could play a role in preventing maternal immuno-rejection at the implantation stage.

A protein methylase from calf-lifer nuclei was partially purified by sonication of the nuclear pellet at high ionic strengh, chromatin removal and ammonium sulphate fractionation on the solubilized activity.