Immunofluorescence in Goodpasture syndrome shows which pattern?

Immunofluorescence in Goodpasture syndrome shows which pattern?

• A. Granular IgG deposits
• B. Linear IgG deposits
• C. No IgG deposits
• D. C3 deposition only

Answer: (B)

In Goodpasture syndrome, autoantibodies target the basement membranes of the kidney and lungs, leading to a type II hypersensitivity reaction. On immunofluorescence, this shows up as a smooth, continuous line of IgG along the glomerular and alveolar basement membranes—a linear pattern. The reason this pattern occurs is that the antibodies bind along the entire basement membrane rather than in discrete clumps, reflecting a uniform antigen distribution along the membrane. Complement can be activated and C3 may also be seen along the membranes, but the hallmark is the linear deposition of IgG. By contrast, immune complex–mediated diseases produce a granular, punctate (lumpy-bumpy) staining pattern along the basement membranes. Absence of IgG would not fit the autoimmune targeting seen in Goodpasture.

In Goodpasture syndrome, autoantibodies target the basement membranes of the kidney and lungs, leading to a type II hypersensitivity reaction. On immunofluorescence, this shows up as a smooth, continuous line of IgG along the glomerular and alveolar basement membranes—a linear pattern. The reason this pattern occurs is that the antibodies bind along the entire basement membrane rather than in discrete clumps, reflecting a uniform antigen distribution along the membrane.

Complement can be activated and C3 may also be seen along the membranes, but the hallmark is the linear deposition of IgG. By contrast, immune complex–mediated diseases produce a granular, punctate (lumpy-bumpy) staining pattern along the basement membranes. Absence of IgG would not fit the autoimmune targeting seen in Goodpasture.