Enhanced adhesion of Pasteurella multocida to cultured turkey peripheral blood monocytes

Capsular hyaluronic acid (HA) mediates adhesion of serogroup A strains of P asteurella multocida to elicited turkey air sac macrophages (TASM), In cont rast, freshly isolated turkey peripheral blood monocytes (TPBM) do not bind serogroup A strains. Following culture of TPBM for 6 days in chamber slide s, adhesion of the bacteria to TPBM increased gradually. Incubation in cham ber slides coated with entactin-collagen IV-laminin (ECL) attachment matrix or exposure to phorbol myristate acetate (PMA) further enhanced the adhesi on of P. multocida to TPBM, Addition of IIA, but not Arg-Gly-Asp peptide, t o TPBM culture inhibited bacterial adherence similarly to the inhibition pr eviously reported for TASM, Exposure of TPBM to monoclonal antibody directe d against IIA-bindinng cell surface proteoglycan (CD44) decreased binding o f P. multocida. Collectively, these findings indicate that P. multocida adh esion to TPBM is mediated by capsular RA and can be increased by culture on ECL attachment matrix Or PMA exposure, Additionally, the findings suggest that the capsular mucopolysaccharide of serogroup A strains of P multocida recognizes an isoform of CD44 expressed on cultured TPBM.