Simple colorimetric cell-cell adhesion assay using biotinylated lymphocytes

A new approach for quantitating lymphocyte adhesion based on labeling the lymphocyte plasma membrane with water-soluble biotin was developed. Adherent biotinylated lymphocytes were quantitated by measuring OD values of a colored substrate representing the amount of bound avidin-peroxidase. The lymphocyte adhesion assay based on the high affinity of avidin to biotin was considerably more sensitive when compared to rose bengal or [³H]thymidine labeling methods. The end-point of sensitivity is approximately 1000 lymphocytes which is clearly an improvement over the rose bengal or radiolabeling techniques with a detection limit of respectively 15 × 10³and 7.5 × 10³ lymphocytes added to wells at the beginning of the assay. The method has the advantage of being rapid and simple and offers an alternative to adhesion assays based on cell ELISAs using cell-specific monoclonal antibodies.