Antigen-antibody reactions in agar. IX. Treatment of antisera and optical densities of precipitin reactions.

The data presented here indicate that for routine use of this technique, one should: a) inhibit the hemolytic complement of all antisera to obtain standard curves with zero intercepts, b) store such decomplemented antisera at subzero temperatures to prevent further changes which might influence O.D. values and c) keep the antiserum-agar mixture in the reaction bath at 56°C for the minimal time needed to charge triplicate reaction tubes to prevent abnormal O.D. increases, particularly those observable at higher antiserum concentrations.