Serological reactions of glycolipids from streptococcal L-forms

Parent bacteria and L-forms of some streptococci of group A, group D, and Streptococcus MG share common antigens as shown by cross-reactivity in growth inhibition, complement fixation, and Ouchterlony tests. Cross-reactivity between these streptococci or their L-forms with a staphylococcal L-form, or Mycoplasma pneumoniae, was found only rarely and only in low-titer complement fixation tests. Removal of all three serological reactivities from positive antisera by addition of chloroform-methanol (7:3) extracts of the streptococci or their L-forms, and failure to remove activities by protein extracts, indicated the glycolipid nature of the cross-reacting antigenic determinants.