Somebody Rang the Alarm
Asystole

I found a little crack in the skin one night,
Slipped through the door and switched on the light.
A macrophage turned with a look of delight:
"Oh, somebody's staying for a bite."

Pattern-recognition receptors knew my signs,
Microbial patterns rang the warning lines.
Cytokines called through the neighbourhood air,
Neutrophils followed the signals there.
A phagocyte swallowed a friend of mine,
Lysosomes joined the compartment in time.
Enzymes and an oxidative burst—
We'd barely arrived; the welcome got worse.

C3b tags me, C5a calls,
C3a joins the alarm in the halls.
C5b to nine builds a membrane pore;
A Gram-negative guest might escape no more.
Tag me, call them, bring that swarm—
Somebody rang the alarm.

Classical starts when antibodies bind;
C1q can recognise the ones aligned.
Lectin meets sugars on a microbial face;
The alternative pathway keeps up the pace.
C3 tick-over can get it underway,
Susceptible surfaces let it stay.
Three roads meet at C3 convertase:
Cleaving C3 all over the place.

C3b tags me, C5a calls—
My name's on a poster all over the walls.

C3b coats me: opsonisation,
An easier grip for phagocytosis.
C5a draws more fighters near;
Chemotaxis tells them where to steer.
C3a and C5a stir inflammation,
C5b starts the next construction.
Six, seven, eight, then nine join the attack:
A membrane pore called the M-A-C.

Host cells have brakes on the complement race,
Regulators keep the cascade in place.
CD59 guards against the final pore—
A little restraint can protect the floor.
Dendritic cells carry news down the road,
Showing what they found in a lymph node.

C3b tags me, C5a calls,
C3a joins the alarm in the halls.
C5b to nine builds a membrane pore;
A Gram-negative guest might escape no more.
Tag me, call them, bring that swarm—
Somebody rang the alarm.

I came for the sugar, I stayed for the storm.
Somebody, somebody rang the alarm.