Detection of antibody-accessible proteins on the cell surface of Haemophilus influenzae type b

A radioimmunoprecipitation method has been devised which permits the direct identification of those proteins which are both exposed on the cell surface of Haemophilus influenzae type b and accessible to antibody. Both extrinsically and intrinsically radiolabeled cells of this organism were employed as the sources of antigen in radioimmunoprecipitation experiments which involved incubation of intact bacterial cells with antisera. Several different proteins, ranging in apparent molecular weight from 33,000 to 160,000, were shown to be accessible to antibody on the cell surface of this pathogen.