LIPIDS AND IMMUNOLOGICAL REACTIONS IV. Tm~ LIPm PATTERNS OF SPECIFIC PRECIPITATES FROm TYPE I ANTIPNEUMOCOCCUS SERA BY FRANK L. HORSFALL, Jm, M.D., AND KENNETH GOODNER, PH.D

I t has been shown (1) that, after the extraction of lipids, antipneumococcus horse serum fails to give type-specific agglutination or precipitation, and with antipneumococcus rabbit serum these reactions are almost entirely eliminated. If these extractive procedures are carried out in such a manner as to avoid denaturation of proteins the removal of the lipids in no way interferes with the fundamental capacity of the antibody to combine with the specific antigen; lipid extraction merely affects the secondary in vitro phenomena of immunological reactions (1, 2). A tentative hypothesis formulated to explain these results held that antipneumoeoccus antibodies might be lipo-protein complexes. This theory found some support in the fact that the original agglutinating and precipitating properties of the lipid-extracted immune sera could be restored by the addition of certain purified phosphatides, although in this restoration there was a curious selectivity dependent upon the species origin of the antibody. Thus the "essential" phosphatide for antipneumococcus horse serum is lecithin, while that for antipneumococcus rabbit serum is cephalin (1).