Using OmpC protein, BSA-linear peptide conjugate and BSA-cyclic peptide conjugate as antigens in an ELISA assay, the levels of IgA and IgG class anti-OmpC antibodies were determined in the sera of healthy donors, patients with humoral primary immunodeficiencies (PID) and patients with recurrent upper respiratory tract infections (RRTI). This evidence concerns the gene CD79A and pelvic inflammatory disease.