Recycling of ELISA plates for the serological diagnosis of tuberculosis using a Mycobacterium tuberculosis-specific glycolipid antigen

A Mycobacterium tuberculosis-specific glycolipid antigen (diacyl-trehalose - DAT) and a battery of defined sera from tuberculous patients were used to evaluate the reliability of recycling ELISA microplates for serodiagnosis of tuberculosis. The reuse of plates was evaluated by the same ELISA technique before and after recycling with an acid buffer to dissociate and release antibodies from antigen-antibody complexes fixed on used plates. The correlation coefficients for comparisons between several new plates used on different days were always higher than r = 0.90, and the Variation between tests was always lower than 12%. For comparisons performed systematically between new plates and recycled plates, the values were variable. Up to the fifth recycling, the correlation coefficient was higher than r = 0.60. From the sixth recycling, correlation coefficient values fell to r = 0.381. The results obtained with recycled plates washed manually were much poorer than those obtained after automatic washing. The results described in this report demonstrate that an ELISA test can be performed on recycled plates under the conditions described.