Question

Properdin is
(A)Neurohormone for stimulating body activities
(B)Plasma protein that destroys foreign RBC's
(C)Plasma protein involved in defense against certain bacteria and viruses
(D)Both B and C

Answer 1

Hint: Properdin is a gamma globulin protein and it is known that it participates in some specific immune responses. It takes part in tissue inflammation as well as the engulfing of pathogens by phagocytes.

Complete answer:
 Out of the complement activation that stabilizes the alternative pathway convertases, Properdin is the only known positive regulator. It's found within the serum of more complex animals.
Due to properdin, the complement system is activated by IgA immune complexes and bacterial endotoxins, polysaccharides, and cell walls, and leads to producing anaphylatoxins, opsonins, chemotactic factors, and therefore the membrane attack complex, all of which help to fight with the pathogens. It is present in Plasma protein that destroys foreign RBCs and is involved in defense against certain bacteria and viruses.

Additional Information: The complement protein properdin is a highly charged plasma glycoprotein. In contrast to most complement components that are being produced by the liver, properdin is especially synthesized by leukocytes, including T cells, monocytes, and mast cells. The protein is additionally stored within the secondary granules of neutrophils from which it's released upon stimulation. The contribution of neutrophils to the entire protein levels found in plasma is highlighted by the association between chemotherapy-induced neutropenia and a decline in circulating properdin levels. Normal systemic levels of human properdin generally cover an outsized home in the healthy control group and are reported during a range from 5 to 45 μg/ml
So, the correct answer is ‘Both B and C’.

Note: Properdin deficiency is inherited and defined as an X-linked recessive trait. The protein could also be absent or reduced within the serum, counting on the precise mutation. Patients with properdin deficiency have the absent function of the choice pathway. Similarly, serum bactericidal activity for a few strains of meningococci is reduced in properdin-deficient serum.