Plantago lanceolata (English plantain) pollinosis in Japan

Objective: The objective was to ascertain the prevalence of Plantago lanceolata (English plantain) pollinosis in Japan. Methods: A total of 160 patients with allergic rhinitis were examined at the Hokkaido University Hospital Otolaryngology Clinic between January 2002 and December 2003. We investigated the frequency of P. lanceolata antigen-specific immunoglobulin E (IgE) antibody-positive serum using the radioallergosorbent test (RAST), the P. lanceolata pollen counts in the Sapporo area and the clinical symptoms of patients with allergic rhinitis caused by this pollen. Results: P. lanceolata pollen was dispersed throughout the Sapporo area from mid-May to early September, peaking in the latter half of May. The airborne pollen count showed little variation between years. The P. lanceolata RAST-positive rate was 12.8%, which was close to those for ragweed and sagebrush. All subjects showed overlapping antigen sensitization, that is, none displayed sensitization (by RAST) exclusively to P. lanceolata. The onset of subjective symptoms peaked in June and the symptoms worsened from April to October. Conclusion: P. lanceolata was dispersed over a long period, from mid-May to early September. The P. lanceolata RAST-positive rate (12.8%) was similar to those for sagebrush and ragweed, which are dispersed during the fall. These results suggest that P. lanceolata is an important causative agent of pollinosis in Japan.