Allergic Reactivity of <i>Parthenium hysterophorus</i> (Santa Maria Feverfew) Pollen: An Unrecognized Allergen

Abstract

Parthenium hysterophorus (PH), a member of the Asteraceae, is a ubiquitous weed found in great profusion in the United States Gulf coast area. A plant survey carried out in Texas Gulf coast demonstrated that around Corpus Christi, PH is the most prevalent weed. We have studied known ragweed-sensitive patients living in Austin and Corpus Christi, by radioallergosorbent test (RAST) analysis for PH and Ambrosia psilostachya (AP; western ragweed). Nine often patients from Austin were RAST-positive to PH and AP; 8 of the 10 patients had positive scores to both pollen extracts. All of the 8 patients from Corpus Christi were positive to both PH and AP. The Austin group showed a significant correlation between AP and PH RAST scores while no correlation between RAST values was seen in the Corpus Christi group. RAST inhibition analysis in this highly selected population did reveal patients that had true sensitivity to PH pollen alone or who were sensitive to both PH and AP pollen. This suggests that in areas where it is highly prevalent PH pollen is an overlooked cause of allergic disease.

Allergenic Cross-Reactivity between <i>Parthenium</i> and Ragweed Pollen Allergens

“…It is difficult to conclude whether these patients make IgE antibodies directed against epitopes on both the allergens or against one which is cross-reactive with the other [8], In the present study, however, the cross-rcactivity of Parthenium and rag weed pollen allergens was determined using sera of Indian patients who were never exposed to ragweed, which is not found in India. Although RAST inhibition analyses re vealed some differences in the inhibition of binding of IgE antibodies in the individual sera to ragweed and Parthe nium discs, there was significant cross-reactivity between the two allergens.…”

“…3). In an earlier study, sera of 17 of 18 ragweedsensitive patients from Austin and Corpus Christi (Gulf coast areas of Texas, where Parthenium is found in great profusion) had elevated levels of Parthenium-specific IgE [8]. RAST inhibition performed with the sera of a small but highly selected group of patients in this region sug gested that approximately 30% of the entire group was al lergic to Parthenium, while another 10% were sensitive to both Parthenium and western ragweed and the remainder of the patients appeared to be individuals whose major re activity was directed against western ragweed with cross reactivity against Parthenium.…”

“…While RAST inhibition ex periments revealed a significant correlation between the western ragweed and Parthenium scores in the Austin group, a very low correlation was observed between the 2 allergens in the Corpus Christi group. In view of the highly selective and limited number of patients studied and in the absence of data on the binding of specific IgE antibodies to individual allergens, the observations of Wedner et al [8] do not substantiate the extent of allergenic cross-reac tivity between Parthenium and ragweed allergens.…”

“…Other studies indicated that al though skin test correlations show a great tendency for ragweed-sensitive patients to respond to other members of the Compositae, this does not necessarily reflect a cross-reactivity even among members of the same tribe such as Cocklebur and Marshelder [20]. Recently, howev er, the allergenic cross-reactivity between Parthenium and ragweed pollen was demonstrated by skin tests, AB-microELISA [7] and RAST inhibition [8],…”

“…These patients elicited positive skin prick reaction to both Parthenium and ragweed pollen extracts. In view of the high incidence of allergic rhinitis attribut able to Parthenium and ragweed pollen in the Indian and US populations respectively, and reports on their cross reactivity and HLA association [7][8][9], a systematic study was carried out to evaluate the allergenic cross-reactivity of these two taxonomically related pollen allergens. In the present investigation, the cross-reactivity between Parthe nium and ragweed (Ambrosia) pollen allergens was stud ied by skin tests, RAST inhibition and lymphocyte prolif eration experiments in Parthenium-sensitive Indian pa tients (not exposed to ragweed) and ragweed-sensitive US patients to Parthenium and ragweed pollen allergens.…”