Lance field grouping of streptococci is done by using :
M protein
Group C peptidoglycan cell wall
Group C carbohydrate antigen
M antigen
Lancefield classification
Classification of β hemolytic streptococci into Group A to V (except I, J) on the basis of group specific C carbohydrate.
Griffith classification
Serological typing of Group A Streptococcus pyogenes on the basis of M proteins into types 1, 2, 3 etc.
Group C Carohydrate

Present in middle layer of cell wall.
This antigen is an integral part of cell wall.
Serological grouping of streptococci depend on C carbohydrate for which it has to be extracted from cell wall.