S. Sridhara et al., ANTIGENIC AND ALLERGENIC RELATIONSHIPS AMONG AIRBORNE GRASS POLLENS IN INDIA, Annals of allergy, asthma, & immunology, 75(1), 1995, pp. 73-79
Background: Pollen from grasses (Poaceae) are predominant aeroallergen
s throughout the world including tropical countries. Studies from USA,
Europe, and Australia have shown extensive allergenic/antigenic cross
reactivity among the grass pollen allergens prevalent there. No such
information is available about airborne grass pollens of tropical coun
tries. Objective: The present study was undertaken to explore common a
ntigenic/allergenic components, if any, of five important grass pollen
s of India. Methods: Intradermal tests (ID) were performed with pollen
extracts of Cenchrus, Cynodon, Imperata, Pennisetum, and Sorghum in p
atients with nasobronchial allergy. ELISAs were performed for estimati
ng the allergen-specific IgE in sera of patients eliciting markedly po
sitive ID response (2+ to 4+). To detect cross reactivity, ELISA inhib
ition experiments were carried out using pooled patient sera and five
grasses, individually, as inhibitors with different solid phase antige
ns. To evaluate common antigenic components in Cenchrus, Imperata, and
Pennisetum pollen extracts, rocket immunoelectrophoresis (RIE) and EL
ISA inhibition were conducted using rabbit antisera. Results: Among 13
3 patients, Cynodon extract elicited markedly positive skin reactivity
in most patients followed by Pennisetum, Imperata, Cenchrus, and Sorg
hum. A large number of patients showed markedly positive skin reaction
s and enhanced specific IgE levels to more than one grass pollen extra
ct. ELISA inhibition experiments showed different degrees of cross rea
ctivity among the grass pollens studied. Rocket immunoelectrophoresis
and ELISA inhibition using rabbit antisera with homologous and heterol
ogous pollen revealed the presence of shared antigenic components in C
enchrus, Imperata, and Pennisetum extracts. Conclusion: The varied dos
e-response curves obtained with ELISA inhibition using different inhib
itors suggest the presence of both common and specific antigens/allerg
ens in the grass pollens studied. Based on the extensive immunologic c
ross reactivity, among the tropical grass species, it may be possible
to use mixed allergen preparations for allergy diagnosis and immunothe
rapy.