Question

In a patient with systemic lupus erythematosus (SLE) who exhibits hypocomplementemia, which class of complement proteins is most commonly reduced in patients with this disease?

A. Class I complement proteins
B. Class II complement proteins
C. Class III complement proteins
D. Class IV complement proteins
E. Class V complement proteins

Answer 1

In SLE, Class III complement proteins are most commonly reduced due to the formation of immune complexes that activate and consume these proteins.

Step-by-step explanation:

In patients with systemic lupus erythematosus (SLE) who exhibit hypocomplementemia, the class of complement proteins most commonly reduced is Class III complement proteins. SLE is known to cause type III hypersensitivity reactions where soluble antigens, such as DNA and other nuclear material, form immune complexes with antibodies.

These immune complexes can deposit in various tissues, often precipitating along blood vessel linings and locally activating complement, leading to a consumption of the complement proteins, particularly those in the Class III category, which includes C3 and C4 components.