microcapsules for effecting an immune response , especially through agglutination reaction , comprise an antigen or antibody bound to functional groups , such as amino groups , carboxy groups , etc ., on a wall surface of the microcapsules via cross linking agents , such as polyfunctional isocyanates , isothiocyanates , etc . the antigen or antibody is strongly bound to the wall surface of the microcapsules to thereby achieve excellent detection sensitivity .