Aqueous Ragweed Extract Research Articles

Allelopathic effect of ragweed (Ambrosia artemisiifolia L.) on seed germination and early seedling growth of barley (Hordeum vulgare L.) and white clover (Trifolium repens L.)

Allelopathy is a unique phenomenon in nature that refers to direct or indirect, positive or negative, impact of one plant (including microorganisms, insects, and herbivores) on another plant through chemical secretions (allelochemicals). Ambrosia artemisiifolia (ragweed) is a well-known invasive plant possessing allelochemicals that have been found to inhibit the growth and development of plants in their immediate environment. This study aimed to determine the allelopathic impact of the aqueous leaf extract isolated from ragweed leaves (concentrated extract, 1:2, 1:4, and 1:8) on seed germination and early seedling growth of barley (Hordeum vulgare L.) and white clover (Trifolium repens L.). The examined aqueous extract of ragweed had a higher inhibitory effect on the germination of white clover seeds compared to barley. The germination of barley seeds was the lowest at the concentrated leaf extract (up to 70%), while the same process in barley seeds was not determined at this concentration. In the other treatments, germination was significantly lower in both examined species compared to the control. Shoot and root growth of both researched species was inhibited in all treatments compared to the control. The obtained results indicate that the aqueous ragweed extract significantly inhibits the growth of roots and shoots of both tested species, which increases the need for more intensive research on this topic.

Clinical aspects of allergic disease: A double-blind study of the discontinuation of ragweed immunotherapy

Background: Immunotherapy effectively treats the symptoms of allergic rhinitis and improves its pathophysiology. We studied whether the effects of immunotherapy on the early response to nasal challenge with antigen and seasonal symptoms persist after discontinuation. Methods: Twenty subjects with ragweed allergy who were receiving immunotherapy and who had nasal challenges performed before initiation of treatment were selected. The patients had been receiving maintenance therapy with aqueous ragweed extract at a dose of 12 μg of Amb a 1 equivalent for a minimum of 3 years, at which point they were randomized to receive either placebo injections or to continue with the maintenance dose. Nasal challenges were performed before and 1 year after randomization. Nasal challenges were monitored by counting the number of sneezes and measuring histamine, N-α-tosyl-L-arginine methyl ester–esterase activity, and kinins in recovered nasal lavages. In the same year symptom diaries were collected during the ragweed season. Results: The initial immunotherapy significantly reduced responses to nasal challenge in both groups. The group continuing to receive active treatment showed no significant changes from the response before randomization. In contrast, the group randomized to placebo treatment showed a partial return of histamine, kinins, and N-α-tosyl-L-arginine methyl ester–esterase in nasal secretions and the numbers of sneezes. IgG antibodies to ragweed declined only in the group switched to placebo treatment. Seasonal rises of IgE antibodies to ragweed did not return during the first season after treatment was stopped. Symptoms reported during the ragweed season were not different between the groups. Conclusions: One year after discontinuation of ragweed immunotherapy, nasal challenges showed partial recrudescence of mediator responses even though reports during the season appeared to indicate continued suppression of symptoms. (J Allergy Clin Immunol 1997;100:293-300.)

Local nasal immunotherapy: Efficacy of lowdose aqueous ragweed extract

In previous studies preseasonal local nasal immunotherapy (LNIT) with moderate doses of aqueous ragweed extract (mean total dose 59 micrograms of AgE and 139 micrograms of AgE) was an effective treatment for ragweed hay fever; however, local adverse reactions during therapy were common. This study evaluated the clinical and immunologic responses to LNIT by use of lower doses of aqueous ragweed extract in order to minimize these adverse reactions. Patients were administered preseasonal LNIT for 7 wk and received a mean total dose of 4.7 micrograms of AgE. During the ragweed season, symptom/medication scores (SMS) of the treated patients were equivalent to SMS of untreated patients. Serum ragweed-specific IgE and nasal secretory ragweed-specific IgA rose slightly in the treated patients but not to the extent observed in previous studies. After the ragweed season treated and untreated patients had a substantial increase in serum ragweed IgE antibody titers. No correlation could be found between antibody responses and SMS. This study indicates that LNIT with lower doses of aqueous ragweed extract is clinically ineffective.

Comparison of Rinkel injection therapy with standard immunotherapy

We compared the results of a controlled, double blind study of standard immunotherapy (SIT) in subjects with ragweed hay fever during 1980 with the results of our study of Rinkel injection therapy (RIT) in a group of subjects with ragweed hay fever in 1979. Both groups were of comparable sensitivity. During the 1980 hay fever season in Milwaukee, 20 subjects with atopic rhinitis due to ragweed pollen (eight from the 1979 group treated with RIT) were given SIT (Tr), while 14 matched subjects (eight from the 1979 placebo group) were treated with a histamine placebo (Pl). The same glycerinated aqueous ragweed extract and glycerinated histamine placebo were used in both studies. The mean cumulative dose of ragweed extract in the 1980 study was 5391 PNU (20.1 μg of antigen E [AgE]) as compared with 41.5 PNU (0.16 μg of AgE) in 1979. Results indicated a significantly lower weekly mean symptom score (SxSc) in the Tr group compared with that of the Pl group in 5 of the 6 wk that ragweed pollen was counted in 1980. Weekly mean medication score (MxSc) and physical exanination score (PESc) showed similar but less striking differences. The mean seasonal SxScs, MxScs, and PEScs of the SIT Tr group were significantly lower than those of the Pl group in 1980 as well as those of the RIT Tr group in 1979. The same indices were also significantly lower in 1980 by paired analyses in the subset of eight subjects treated in both years. RAST scores showed a significant decrease in the “after season” means in the Tr group as compared with the Pl group in 1980 but not in 1979 (analysis of covariance). We conclude that SIT is more effective than a placebo or RIT in reducing SxSc, MxSc, and PESc as well as in diminishing postseason RAST values. We cannot recommend therapy as proposed by Dr. H. J. Rinkel for clinical use at this time.

Comparisons of alum-precipitated and unprecipitated aqueous ragweed pollen extracts in the treatment of hay fever

In 1969 and 1970, groups of patients with ragweed hay fever never before treated were started on preseasonal courses of immunization with an alum precipitate of aqueous ragweed extract. A comparison between these two groups of patients and a similar group of patients treated with unprecipitated aqueous extract in 1968 shows that treatment with alum precipitate was safely initiated with fewer injections even though a higher dose was administered. The larger cumulative dose appeared to give better IgG antibody responses and greater relief of symptoms. A repeat preseasonal course the next year again required fewer injections of the alum-precipitated extract than a repeat course of aqueous extract.

The role of ragweed pollen in autumnal asthma

Thirty-nine ragweed-allergic seasonal asthmatics were studied from 1972 to 1974. After quantitative skin tests, antigen E-induced leukocyte histamine release, quantitative inhalation bronchial challenge with ragweed extract to determine PD 35 (provocation dose of allergen causing 35% decrease in specific airways conductance), and radioallergosorbent test (RAST) determinations were done, patients were paired based on PD 35 values and randomly assigned to treatment or placebo groups, receiving either aqueous ragweed extract or placebo prior to the 1973 ragweed season. Treated patients received a mean cumulative dose of extract equivalent to 11.7 μg antigen E (4,180 protein nitrogen units [PNU]). Twenty-nine patients were followed through the ragweed season with daily symptom diaries and biweekly physician examinations. Severity of disease was not predictable by PD 35 data, skin tests, leukocyte histamine release, or radioallergosorbent test (RAST) values. Although all patients were ragweed-allergic by objective tests, only 13 29 had asthma symptoms correlating with ragweed counts. Mold spore counts were related significantly to symptoms in some patients. Asthma and hay fever symptoms correlated significantly in 24 29 patients. This dose of immunotherapy caused no significant difference to be found in asthma or hay fever symptoms in treated versus placebo patients for the 1973 reporting period as determined by physician evaluations or daily symptom diaries. No patients showed significant improvement in PD 35 values after treatment in 1973. Similar findings were obtained for a smaller group of patients followed through the 1974 ragweed season who received a mean dose of 31.2 μg antigen E (11,140 PNU). The failure of these patients to show a response to immunotherapy could be due to a combination of the relatively low dose of ragweed extract and their sensitivity to other allergens.

Trials of alum-precipitated pollen extracts in the treatment of hay fever

Immunotherapy (desensitization) of hay fever with aqueous extracts of pollen is limited to rather small immunizing doses because of the risk of allergic or anaphylactic reactions. Alum-precipitated pollen extracts are absorbed more slowly, and larger doses may be given in fewer injections with a reduced rate of untoward systemic reactions. In a controlled study, alum-precipitated ragweed extract gave therapeutic results in fall hay fever equal to those obtained with aqueous ragweed extract. Immunologic responses to the two types of extract (measured by the technique of histamine release from isolated washed leukocytes) were also similar. Safer antigen preparations which permit higher doses need to be sought further.

The immunogenicity of pyridine-extracted, alum-precipitated ragweed

The immunogenicity of pyridine-extracted ragweed, and pyridine-extracted, alumprecipitated ragweed was determined and compared with that of aqueous ragweed extract by several immunologic techniques. The results indicated that either the extraction of ragweed with pyridine alone or extraction of ragweed with pyridine and subsequent precipitation with alum may alter this allergen's reactivity in human beings and immunogenicity in animals.

Antibody response following immunotherapy in ragweed hay fever: Allpyral vs. whole ragweed extract

The antigenicity of commercially available ragweed pollen extracted with pyridine and precipitated with alum (Allpyral) was compared with that of aqueous ragweed extract. The antibody response was measured by the inhibition of histamine release from sensitive human leukocytes challenged with either ragweed antigen E or whole aqueous extract. A group of patients treated with aqueous extract had a significantly greater antibody response than a similar group treated with Allpyral, even though the latter received 30 times as much antigen. Another comparison showed that patients who had received high dosage Allpyral therapy (average: 0.80 mg. of protein N. or 80,000 PNU) had antibody levels which did not differ significantly from those of untreated control patients.

Sensitization of human subjects after multiple intracutaneous injections of aqueous ragweed extract

Injections of aqueous ragweed extract are generally not thought to be capable of sensitizing ragweed-negative skin reactors. A review of our passive transfer recipients showed that of 22 recipients challenged with aqueous ragweed extract on more than two occasions, 3 developed positive ragweed skin tests. One of these recipients became sensitized and lost the sensitivity in time only to become sensitized again when challenged on one occasion.

Histamine release from leukocytes of hypersensitive individuals: II. Reduced sensitivity of leukocytes after injection therapy

Four ragweed-sensitive patients were treated by courses of injections of aqueous ragweed extract. Specific histamine release from peripheral leukocytes and circulating antibody to purified ragweed antigen were measured at various times. During treatment, a progressive increase was observed in the concentration of antigen required to release a significant proportion of the total cellular histamine. No marked changes occurred in any patient before a total of at least 20, 000 PNU of ragweed extract had been administered. The level of circulating antibody rose during therapy. Changes in serum antibody preceded changes in sensitivity of the leukocytes. After treatment a decrease in symptoms during the next ragweed season was reported by each of the patients.

The effect of alum-precipitated pyridine ragweed extract on guinea pigs: II. Comparison of passive cutaneous anaphylaxis with Arthus reactivity after single low dose

To investigate further the enhanced antigenicity of alum-precipitated pyridine (APPR) as compared to aqueous ragweed extract (ARE), passive cutaneous anaphylaxis (PCA) experiments were performed using sera obtained from the guinea pigs prior to the studies for Arthus reactivity previously reported. 1 The APPR immunized animals produced a greater total number of Arthus reactions, whether moderate or maximum, and the sera from these same animals gave a larger total percentage of positive PCA tests, 39 of 120 (32.5) per cent, than did the ARE immunized animals, 5 of 36 (13.8 per cent). Chi square for this difference was 4.737 and is significant at the 5 per cent level. The APPR immunized animals appeared to develop two types of antibodies more consistently than the ARE immunized. Their sera gave positive PCA reactions earlier after immunization and with lower single doses of APPR than did ARE immunized animals. With immunizing doses of 10 μg of protein N or below, antibodies persisted longer in APPR immunized animals. On day 136, 10 of 10 animals immunized with this dose of APPR gave positive Arthus reactions and their sera produced 7 of 10 positive PCA tests. On the other hand, none of the ARE immunized animals developed Arthus reactions nor did their sera produce positive PCA tests.

Skin-sensitizing antibody titer: III. Relationship of the skin-sensitizing antibody titer to the intracutaneous skin test, to the tolerance of injections of antigens, and to the effects of prolonged treatment with antigen

1. 1. The intracutaneous skin test tends to vary directly with the skin-sensitizing antibody titer. However, individual variations are so great that titer cannot be determined from the skin test. 2. 2. The doses of aqueous ragweed extract tolerated by patients vary inversely with the skin-sensitizing antibody titer. 3. 3. Development of blocking antibody increases the tolerance for injected extracts. 4. 4. Patients with high titers of skin-sensitizing antibody are more likely to have constitutional reactions to emulsions of ragweed pollen extract even with lower doses of antigen. The titer of skin-sensitizing antibody is a helpful guide in determining the dose of emulsified pollen extract to be used. 5. 5. Prolonged treatment with injections of aqueous ragweed extract is accompanied by a decrease in the titer of skin-sensitizing antibody. This decrease is greatest between the first and fifth year of treatment but continues up to 20 years. Comparative studies of untreated patients and of patients who, after 1 or 2 years of treatment, were untreated for an average of 9 years suggest that this decrease in titer of skin-sensitizing antibody results directly from the treatment and not from the increasing age of the patient or duration of hay fever.

Studies in absorption of ragweed antigen following the injection of alum-precipitated pyridine-ragweed complex in man

1. 1. By means of the reverse passive transfer technique it was not possible to demonstrate the absorption of free ragweed antigen from the site of injection of alum-precipitated pyridine-ragweed complex (APPR) in nonatopic subjects. 2. 2. Direct skin tests with a strong ragweed extract in subjects injected with APPR failed to reveal induced sensitivity to ragweed antigen, as evidenced by the absence of delayed or immediate skin reactions. 3. 3. Direct tests on specific ragweed serum-sensitized sites with APPR were negative, whereas tests with aqueous ragweed extract in comparable concentrations were strongly positive. 4. 4. Skin sites in nonatopic subjects sensitized with a potent ragweed reagin-containing serum failed to detect free ragweed antigen following the injection with APPR.

Antibody studies in constitutional reactions resulting from injections of ragweed pollen extract

1. 1. Skin sensitizing antibody titers of patients having constitutional reactions to ragweed were significantly higher than those found in any group of skin test, positive, symptomatic or asymptomatic, treated or untreated patients. 2. 2. Blocking antibody titers of patients who had constitutional reactions were lower than those found in the group of patients treated with high doses of aqueous extract and in patients who had received the ragweed emulsion, but were comparable to those found in patients receiving a similar amount of aqueous ragweed extract. 3. 3. Hemagglutinating titers were similar in patients who had constitutional reactions and in those patients receiving low amounts of aqueous ragweed extract but were less than the post-repository group and the group treated with high doses of aqueous extract.

A slowly absorbed gelatin-pollen extract for the treatment of hay fever

1. 1. Gelatin, a slow absorption medium, was mixed with ragweed pollen extracts in an attempt to overcome difficulties encountered with the standard aqueous extracts. 2. 2. A delay in absorption of the active ragweed substance of the gelatin-ragweed extract as compared to the aqueous ragweed extract was noted following subcutaneous injections at passive transfer sites in a series of normal nonsensitive adults. 3. 3. A series of ninety-five adult patients suffering from ragweed hay fever symptoms were treated preseasonally with the gelatin-ragweed extracts. Another group of ninety-five adult patients were treated with the standard aqueous extracts during the same period. Twenty-two patients of the first group continued their treatment on a monthly basis during 1940 after having completed a course of preseasonal injections. 4. 4. A greater tolerance for the ragweed-gelatin extract was noted; higher maximum dosages (often twice the amount attained with the aqueous extracts) were given with safety and with half the number of injections. 5. 5. Constitutional reactions were milder and occurred infrequently. 6. 6. More effective clinical relief was obtained following treatment with the gelatin-ragweed extracts. 7. 7. An average dosage schedule for preseasonal treatment with gelatin-pollen extracts was determined. It was modified to suit the individual's tolerance. 8. 8. The gelatin extract must be prepared according to the technique outlined if standard and satisfactory results are to be obtained. 9. 9. At present the chief value of the gelatin extracts is in the treatment of hay fever patients so sensitive as to accept poorly the usual aqueous pollen therapy. 10. 10. Further studies are in progress to determine whether the use of the more slowly absorbed gelatin extracts will result in a more sustained and lasting immunity.

Alum-ragweed precipitate: Preparation and clinical investigation: Preliminary report

1. 1. Alum-ragweed precipitate is an alum-modified ragweed extract. The method of its preparation is described. 2. 2. Alum-ragweed precipitate is an effective antigen for sensitizing guinea pigs to ragweed, which confirms the work of previous authors. 3. 3. Local and systemic reactions from intracutaneous and subcutaneous injections of alum-ragweed precipitate in ragweed sensitive patients are similar to those produced by equal protein nitrogen concentrations of aqueous ragweed extracts. 4. 4. A slight delay in the absorption of the active pollen fractions of alum-ragweed precipitate as compared to aqueous ragweed extracts, was noted following subcutaneous injections in a series of normal adults. 5. 5. The preseasonal treatment of a series of 24 ragweed sensitive patients with alum-ragweed precipitate is reported. 6. 6. The active ragweed components of alum-ragweed precipitate are apparently identical to those of aqueous ragweed extract. 7. 7. Further investigations are indicated, particularly: (a) variations in the chemical preparation of alum-ragweed precipitate, using greater concentrations of alum than 1 per cent; (b) variations in the methods of therapeutic administration.