Does an allergic-type pattern with elevated eosinophils and basophils reflect Type-2 activation that co-occurs with autoimmune disease?

While traditional models of immunology once viewed autoimmune and allergic responses as mutually exclusive, modern research establishes that Type-2 (Th2) immune activation frequently co-exists with and contributes to the pathology of autoimmune diseases.

Mechanistic basis of Type-2 activation

Elevated eosinophil and basophil levels serve as primary markers for Type-2 immune activation. These cells are not merely passive indicators but active drivers of the Th2 environment:

• Basophils as Initiators: Basophils act as early initiators of the Th2 response by producing IL-4, which directs naive CD4+ T cells to differentiate into Th2 cells. They also express MHC class II and OX40 ligand, directly facilitating Th2 polarization.
• Eosinophil Recruitment: Eosinophils are recruited and differentiated primarily by IL-5. Once present, they contribute to tissue remodeling and inflammation.
• Synergistic Relationship: Basophils function as "gatekeepers," coordinating the recruitment of eosinophils into tissues via endothelial interactions. When basophil activation is suppressed, researchers observe a corresponding decrease in the Th2 cytokine triad (IL-4, IL-5, and IL-13) and reduced eosinophilic inflammation.

Co-occurrence in autoimmune disease

The paradigm that autoimmunity is solely driven by Th1 or Th17 pathways has been revised to include Type-2 activation across several conditions:

• Th2-Driven Autoimmunity: Type-2 responses are central to the pathogenesis of IgG4-related disease (IgG4-RD), systemic sclerosis-associated interstitial lung disease (SSc-ILD), and membranous nephropathy. In these cases, Th2 cytokines drive critical processes like B-cell dysregulation and fibrosis.
• Systemic Conditions: Conditions such as systemic lupus erythematosus (SLE) and Sjögren’s syndrome are frequently characterized as $TH_2$-dominant, illustrating that allergic-type immune patterns can be a consistent feature of systemic autoimmunity.
• Bystander Activation: Environmental triggers or microbial dysbiosis can amplify Th2 responses simultaneously with autoimmune pathology, a process known as "bystander activation."

Bottom line

An allergic-type immune pattern with higher eosinophils and basophils is a scientifically validated reflection of Type-2 immune activation. This activation is not limited to allergies but frequently co-occurs with and drives the progression of various autoimmune diseases through cytokine-mediated B-cell activation and tissue fibrosis.