David A. Power

IgA Nephropathy Is Not a Rare Disease in the United Kingdom

A retrospective analysis of all renal biopsies performed in the Grampian Region of Scotland during 1977-1980 revealed that IgA nephropathy was the most frequently encountered glomerular lesion. The commonest indications for renal biopsy were the presence of asymptomatic urinary abnormalities (90/184; 48.9%) especially asymptomatic haematuria (42/184; 22.8%). A histological diagnosis was made in 36 of the 42 patients presenting with asymptomatic haematuria (85.7%); 16 of the 26 cases of IgA nephropathy presented in this way. Overall, IgA nephropathy was detected in 14.1% of all biopsies and accounted for 21.8% of primary glomerular diseases. This study indicates that IgA nephropathy is apparently more common in Grampian than elsewhere in the United Kingdom. However, it is suggested that this does not represent a true variation in the prevalence of the condition; IgA nephropathy is probably a common cause of haematuria in the United Kingdom.

Diagnostic value of urinary N-acetyl-β-d-glucosaminidase, its isoenzymes and the fractional excretion of sodium following renal transplantation

Daily total urine N-acetyl-beta-D-glucosaminidase activity, isoenzyme profile and fractional excretion of sodium were measured in 13 consecutive renal transplant patients. Rejection episodes were clinically diagnosed in 12 patients, 11 of whom (92%) showed an increased enzymuria either before or during the onset of clinical signs. The ratio of the two major isoenzymes (A/B) fell during 10 episodes (83%) and in six of these (50%) increased levels of the minor isoenzyme forms were observed. Increased fractional excretion of sodium was associated with nine (75%) of the episodes. Increased fractional excretion of sodium with a raised total enzymuria accompanied by a reduced A/B ratio and an increased proportion of the minor isoenzyme forms occurred in eight (67%) of the rejection episodes. The use of these measurements in the diagnosis of episodes of acute rejection in renal transplantation is discussed.

POSSIBLE MECHANISM OF ACTION OF TRANSFUSION EFFECT IN RENAL TRANSPLANTATION

The mechanism by which blood transfusions given before renal transplantation improves allograft survival was studied in 31 transplant recipients. The presence of non-cytotoxic, Fc receptor blocking antibodies to donor and leukaemic B lymphocytes in pre-transplant sera correlated with both improved graft survival (p less than 0.03 and less than 0.1, respectively) and the number of blood transfusions given (p less than 0.05 and less than 0.03, respectively). Moreover, 6 out of 10 previously untransfused prospective transplant recipients developed these potentially protective antibodies during a course of elective blood transfusions. These results indicate that such non-cytotoxic, Fc receptor blocking antibodies in pretransplant recipient sera (a) are associated with improved allograft survival, (b) correlate with the number of blood transfusions given, and (c) can develop in response to blood transfusion.

Fetus as an Allograft: Noncytotoxic Maternal Antibodies to HLA-Linked Paternal Antigens

ABSTRACT: A cellular enzyme‐linked immunospecific assay (CELISA) was used to monitor maternal humoral responses in human pregnancy. Noncytotoxic IgG antibodies to paternal lymphocytes were detected in sera from 6 of 20 normal first trimester primigravidae and 6 of 13 multiparae. No antibody activity against lymphocytes from their partners was detected in sera from any of the 15 nulliparous women. The differences in antibody response between primigravidae and nulliparae (P = 0.024) and between multiparae and nulliparae (P = 0.005) were statistically significant. Lymphocytotoic antibodies to T‐ and B‐lym‐phocytes were present in sera from three multiparae, but from none of the women in the other two groups. Family studies indicated that the noncytotoxic pregnancy‐associated maternal antibodies were directed to HLA‐linked antigens (P < 0.001). Evidence obtained using cell panels and platelet absorption suggested, however, that these antibodies were not directed to the currently recognized HLA specificities (HLA‐A, ‐B, ‐C, or ‐DR).

Maternal alloantibody responses during early pregnancy detected by a cellular enzyme-linked immunospecific assay

Using a cellular enzyme-linked immunospecific assay (CELISA), we have examined sera from nulliparous women and women in the first trimester of a first or subsequent pregnancy for the presence of antibodies directed to surface determinants on peripheral blood lymphocytes from unrelated donors. Maternal antibody activity was found in sera from 1/13 nulliparae, 19/37 primigravidae, and 8/12 multigravidae. Cytotoxic antibody activity was present in 3/12 multigravidae but in no other group. Absorption with packed, pooled platelets did not remove the antibody activity from three of the primigravid sera; unabsorbed sera, however, bound equally well to T and B lymphocytes. These data suggest that the antibody detected by CELISA is not directed to any of the classical HLA antigen series (-A, -B, -C, or -DR) but may be directed to the HLA linked non-class I HT antigen system.

The Detection of Antibodies in Pregnancy: A Comparison of Two Assay Systems

ABSTRACT: In this study we have compared the ability of two assay systems, erythrocyte antibody rosette inhibition (EAI) and cellular enzyme‐linked immunospecific assay (CELISA) to detect maternal alloantibody activity during pregnancy. Antibody activity to antigens on paternal lymphocytes was present in nine of 23 primigravid sera tested by EAI and in seven of 23 by CELISA. In multiparous sera, antibodies directed to paternal lymphocytes were detected in 11 of 15 individuals by EAI and in six of 15 by CELISA. The techniques correlated significantly when assaying the humoral response in sera from multiparous women. The lack of correlation when assaying primigravid sera suggests that both assays encounter difficulty in detecting the low titres of antibodies present.