GAS alphamers confer uptake of GAS M1T1 cells by human phagocytes in the presence of mouse and human polyclonal IgG in an alpha-Gal-specific manner. Green fluorescent GAS cells were pre-incubated with the indicated 5′-α-Gal conjugated GAS alphamers, non-alpha-Gal GAS aptamer, the respective control alphamer/aptamer, or vehicle only. Then, polyclonal mouse IgG or human IgG (hIVIG) and, finally, purified human blood neutrophils were added to the bacteria. After 20 min of co-incubation, the phagocytes were washed and examined for uptake of GAS by fluorescence microscopy. Extracellular bacteria were distinguishable from intracellular bacteria by counterstaining with ethidium bromide. Samples were run in quintuplicate or hexuplicate, and average percentages of neutrophils with phagocytosed bacteria ± SD are shown in the graphs. ***p<0.00005, unpaired t test, GAS alphamers vs. respective control alphamers and vehicle controls. Representative data of one experiment for each data set of at least two performed are shown