Reclamation of streptococcal cells for reuse in adsorption of antisera.

One of the major problems in the production of diagnostic antisera for the specific Griffith types of Lancefield Group A hemolytic streptococci is the accumulation of sufficient volumes of cells for adsorption processes. To minimize this problem a procedure was developed for the reclamation and reuse of the adsorption cells. The technique is as follows: Packed cells, after use for adsorption, are suspended in 4 to 5 volumes of N/5 HCl in physiological saline and refrigerated at 4 to 10 C overnight. The acid-cell suspension is centrifuged and the cells washed 3 times in 4 to 5 volumes of physiological saline. The second saline suspension is adjusted to pH 7.0 to 7.2 with N/l NaOH. Cells treated in the above manner are used routinely for 4 to 5 adsorptions. The maximum number of times they can be so handled has not been determined. However, each of 2 batches of cells has been used for 8 adsorptions with no apparent change in their adsorptive capacity. Untreated cells and cells washed only with physiological saline have not proved satisfactory for reuse. Resuspension of the tightly packed cells for the acid and saline washes is effected with a midget household electric mixer, the blade of which fits easily into a 50 ml centrifu'ge tube. Ten to 20 seconds agitation with the mixer yields as even a suspension as 5 to 10 minutes manipulation with a pipette. There has been no investigation of the efficacy of treatment of the cells with other concentrations of HCI, with other acids, with alkalis, or with high salt concentrations. Although the optimum time of exposure of cells to acid has not been determined, no difference is observed with treatments as short as 4 hours or as long as 4 days. Overnight exposure was adopted arbitrarily as a matter of convenience. No effort has been made to detect antibody in the supernate after acid treatment. In spite of these voids in information regarding the procedure, it is presented at this time because it has proved practical in routine use. It is hoped that the technique can be adapted for use in the preparation of other bacterial antisera.