Study on the nature of the Goodpasture antigen using a basement membrane-producing mouse tumour.

Autoantibodies in the sera of patients with Goodpasture's syndrome showed a strong reaction in indirect immunofluorescence tests on unfixed, frozen sections of a mouse tumour (EHS sarcoma), previously shown to produce extracellular basement membrane. Anti-basement membrane antibodies from patients with bullous pemphigoid failed to react with the mouse tumour, but showed a distinct reaction with cylindroma tissue. Absorption of Goodpasture sera with tumour homogenate completely abolished their reaction on sections of human and murine kidney. Basement membrane (type IV) collagen and a high molecular weight, non-collagenous glycoprotein were isolated from the tumour matrix and studied in absorption experiments and radioimmunoassays. Little or not reaction was observed with Goodpasture patients' sera indicating that neither of these two proteins is the major antigen involved in the disease. Antigenic material reacting with Goodpasture sera was extracted from the tumour in neutral salt solutions, suggesting that it is a non-collagenous protein.