Abstract: An assay method and kit for a hapten such as theophylline employs a first, latex reagent and a second, antibody reagent. By using a monoclonal antibody of the IgA class in the second reagent, interference by patient rheumatoid factor is prevented.

Abstract: Disclosed is a method for detection for serum antibody and/or microbial surface antigen by radial partition immunoassay. The method of this invention is applicable to (a) the evaluation of a clinical specimen for identification of a microorganism; (b) antimicrobial sensitivity assays for determination of an efficacious antibiotic for use against a specific microorganism; (c) a semi-quantitative determination of viral surface antigen; and, (d) a quantitative method for the determination of the presence of serum antibodies to microbial antigens. In each of the foregoing applications, the analyte of interest can be immobilized within a porous matrix (solid phase) by simple pipetting of the sample onto the prepared matrix. Appropriate reagents are subsequently applied to the matrix to effect immunochemical interaction of a labeled binding material to the surface antigen (or antibody) of the analyte of interest. The portion of the matrix within which such interaction takes place is termed the "reaction zone".