Optimization of the Protocol for Human Immunoglobulin G (IgG) Extraction from Dried Blood Spots

Abstract

Existing protocols for extracting Immunoglobulin G (IgG) from blood spots (DBS) were compared, utilizing fresh, one-week-old, and one-month-old DBS made from a healthy Thai’s blood as the samples. In addition, DBS samples from healthy uninfected villagers obtained from a Malaria survey in 2017 will also be used. To validate the previously published elution protocols and buffers, alterations of elution buffers were applied in a down-selection approach, uncovering the optimal buffer compositions that can elute the highest yield and purity of IgG. The IgG level in the eluates obtained from the elution using NP-40, particularly 0.5% NP-40, which showed the strongest activity in IgG elution, was significantly distinct with the IgG level obtained using the 0.05% Tween-20 buffer, which is the current standard protocol applied in Mahidol Vivax Research Unit (MVRU). While all protocols can relatively extract the IgG from DBS samples, only buffers that contain either NP-40 or ammonium chloride, aside from PBS, can successfully extract IgG from seven-years-old DBS samples at a significant level. In addition, all of the tested protocols were done in the most effective manner, requiring only a low cost, simple equipment, and a short time to be performed in order to find the most applicable protocol that can be utilized during emergency situations in rural areas.