FOWL ANTIBODY .5. INTERACTIONS OF FRESH AND HEATED FOWL SERUM AND OF GUINEA-PIG COMPLEMENT MEASURED BY LYSIS OF SENSITIZED RED CELLS

Abstract

Dilutions of fresh fowl serum up to about 1:100 inhibit the lysis of sensitized red cells by guinea pig complement; this inhibition is decreased by treatments of the serum that also reduce its own haemolytic activity. Studies of this effect are complicated by the fact that fresh fowl serum, when diluted up to 1:32-1:64, lyses sheep red cells with no added haemolysin; with cells sensitized with added haemolysin this lysis is seen in even higher dilutions. Lysis by fowl complement is in turn inhibited by guinea pig complement: the lytic action of 1-2 C''H50 of fowl C'' is blocked by guinea pig serum 1:1000. Thus mixtures of sheep red cells sensitized with a mammalian haemolysin, fresh fowl serum and guinea pig complement possess two distinct haemolytic activities which are mutually inhibitory, giving rise to effects that simulate specific fixation. Heated fowl serum, if present in excess, inhibits lysis by fowl C''; when added in small amounts it supplies a limiting heat stable factor and exhances lysis.