Specific pattern of flea antigen recognition by IgG subclass and IgE during the progression of papular urticaria caused by flea bite.

BACKGROUND Papular urticaria caused by flea bite presents clinical symptoms of a hypersensitivity reaction accompanied by skin lesions. However, the pattern of recognition by different antibody isotypes during the progression of the disease is unknown. This study evaluated variations in immunoglobulin E and immunoglobulin G subclass antibody responses to flea antigens during the progression of papular urticaria caused by flea bite METHODS Twenty-five patients clinically diagnosed with papular urticaria due to flea bite were included. Ten healthy children were included as controls. Recognition of antigens from complete flea body extract by patients and healthy controls was determined using immunoblot assays. RESULTS The results revealed that patients with 2-5 years of papular urticaria evidenced more IgE bands than those with shorter or longer durations of symptoms. In contrast, healthy children showed a predominance of immunoglobulin G1 and immunoglobulin G3. The majority of the recognised antigens were low molecular weight proteins (<90 kDa). Proteins with molecular weights between 16-20, 21-25, and 31-35 kDa showed different patterns of recognition between patients and healthy children. CONCLUSION The predominant specific antibody isotypes vary according to the time elapsed since the onset of symptoms in papular urticaria caused by flea bite.