Questions: Immunodeficiency of C2 and C4 complements is likely to affect MAC formation by the alternate pathway mannan binding pathway all the complement pathways classical pathway

Immunodeficiency of C2 and C4 complements is likely to affect MAC formation by the alternate pathway mannan binding pathway all the complement pathways classical pathway

Transcript text: Immunodeficiency of C2 and C4 complements is likely to affect MAC formation by the alternate pathway mannan binding pathway all the complement pathways classical pathway

Solution

The answer is the last one: classical pathway.

Explanation:

The classical pathway of the complement system is initiated by the binding of antibodies to antigens, which then activates the C1 complex. This activation leads to the cleavage of C2 and C4, forming the C3 convertase (C4b2a) that is crucial for the progression of the pathway.
Immunodeficiency of C2 and C4 would directly impair the classical pathway because these components are essential for its activation and progression.
The alternate pathway does not rely on C2 and C4 for its activation; it is initiated by the spontaneous hydrolysis of C3 and involves different components (e.g., factor B, factor D).
The mannan-binding lectin (MBL) pathway, also known as the lectin pathway, involves MBL binding to mannose residues on pathogens, leading to the activation of MASP-1 and MASP-2, which then cleave C2 and C4. While C2 and C4 are involved, the primary initiation is different from the classical pathway.
All the complement pathways would not be affected by C2 and C4 deficiencies, as the alternate pathway can still function independently of these components.

Therefore, the immunodeficiency of C2 and C4 complements is most likely to affect the classical pathway.

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