Veiled cells are immature dendritic cells found in blood. 

C3a, C4a and C5a proteins are anaphylotoxins. They cause smooth muscle contraction.

sPLA2 (Secreted phospholipases A2) have been shown to promote inflammation in mammals by catalysing the first step of the arachidonic acid pathway by breaking down phospholipids.

C3b and, to a lesser degree, C4b molecules are opsonins.

Post-infectious glomerulonephritis is a kidney disease in which complement component 3 level in the blood gets lowered.

The principle effector function of IgM is complement activation. 

The beta defensins are antimicrobial peptides implicated in the resistance of epithelial surfaces to microbial colonisation, thus beta-defensins act as a chemical barrier and provide immunity to skin.

Factor H is a member of complement activation family.

Mast cells express a high-affinity receptor (FcεRI) for the Fc region of IgE antibodies.

RAG enzymes work as a multi-subunit complex to induce cleavage of a single double-stranded DNA (dsDNA) molecule between the antigen receptor coding segment and a flanking recombination signal sequence.

MPOs are expressed in neutrophil granulocytes. 

Hypocomplementemic urticarial vasculitis syndrome (HUVS) (also called SLE-related syndrome or chronic hypocomplementemic cutaneous vasculitis) is a disorder associated with anti-C1q antibodies that leads to classical pathway activation and chronic decreases in C1, C2, C4 and C3 levels.

IgW antibody is found in group of lobe-finned fishes, including coelacanth and lungfish.

Class II HLA are membrane-bound glycoproteins that are restricted to macrophages and lymphocytes.

IFN-alpha interferon can be used to treat hepatitis B and C infections.