Heterophile anti-mouse immunoglobulin antibodies may interfere with cytokine measurements in patients with HLA alleles protective for type 1A diabetes

Wilson and coworkers (Wilson SB, Kent SC, Patton KT, Orban T, Jackson RA, E xley M, Porcelli S, Schatz DA, Atkinson MA, Balk SP, Strominger JL, Hafler DA: Extreme Th1 bias of invariant V alpha 24J alpha Q T-cells in type 1 dia betes. Nature 391:177-181, 1998) have recently reported raised serum levels of interleukin-4 (IL-4) in anti-islet autoantibody-positive first-degree r elatives of patients with type 1A diabetes who did not progress to diabetes . Protection from diabetes has been noted for several human lymphocyte anti gen (HLA) alleles, such as HLA DR2-DQA1*0102-DQB1*0602, We, therefore, want ed to determine whether this cytokine phenotype was associated with HLA gen es protective for type 1A diabetes. We used a two-site fluoroimmunoassay wi th the same monoclonal antibodies as those reported by Wilson et al, Using this assay, we have found evidence for human heterophile antibodies mimicki ng serum IL-4: all serum IL-4 reactivity was lost if mouse serum or mouse i mmunoglobulin were added to the assay; serum IL-4 activity was bound and th en eluted by protein A/G chromatography; and levels of anti-mouse antibodie s correlated with apparent serum IL-4, This pseudo-IL-4 activity was found in a subset of control subjects, patients with type 1A diabetes, and their relatives and was primarily associated with specific HLA alleles protective for type 1A diabetes (e.g,, DQB1*0602), After adjustment for HLA, positive levels of heterophile antibodies were not associated with protection from diabetes, The confounding effect of protective BLA alleles associated with heterophile antibodies could explain the previously reported association be tween raised serum lL-4 and protection from type 1A diabetes. The mechanism by which specific DQ alleles protect from diabetes and are associated with increased heterophile antibodies is currently unknown.