Clinical value of serum B 1A - and B 1E -globulin levels in adult patients with renal disease.

Abstract

Abstract Serum levels of B1A‐globulin, a metabolic product of the third component of complement, have been investigated by a simple immunochemical method in a group of adult patients with renal disease. A renal biopsy was performed in 100 of 105 adult patients with primary renal disease and in 27 of 51 patients with secondary or other renal disease, enabling classification on histological grounds. Decreased B1A levels were found in acute poststreptococcal glomerulonephritis (APGN) and in some patients with membrano‐proliferative glomerulonephritis (MPGN) and glomerulonephritis associated with systemic lupus erythematosus (SLE). In these three categories of patients B1E‐globulin, the fourth component of complement, was also determined by the same simple immunochemical method. In APGN B1A‐globulin rises to normal levels in 1–4 months after the onset of the disease. The B1E‐globulin is occasionally decreased at a very early stage in APGN, and then returns rapidly to normal levels. In MPGN the B1A level may be constantly low for many years. Some patients, however, demonstrate a change in the level with time. The B1E level is usually normal in this group. A number of patients with MPGN had, at least on a single determination, normal B1A levels. In SLE glomerulonephritis decreased levels of both complement components are found, the B1E‐globulin usually being diminished to a greater extent than the B1A‐globulin. Occasionally only the B1E level is low, which could mean that the determination of B1E‐globulin is of greater significance for the diagnosis of SLE than the determination of B1A‐globulin. Two patients with SLE showed a parallel increase in both complement factors during longterm treatment with large doses of corticosteroids. SLE differs in this respect from APGN, and this suggests a different manner of complement activation. From this group of adult patients it may be concluded that the findings relating to serum B1A levels in children with renal disease are also applicable to adults. In addition, the determination of B1A‐ and B1A‐levels by a simple technique is of value in the differential diagnosis of patients with glomerulonephritis.