Interleukin-4 (IL-4) Induces B cell proliferation, eosinophil and mast cell growth and function, and IgE expression on B cells. Allergic individuals have a greater propensity to produce IL-4. Many dietary lectins induce the activation of IL-4, which implies that for many people the allergic reaction to dietary lectins may be more important than their agglutinating abilities
One of the main immune system Growth Factors. IL4 is a cytokine produced by T cells that regulates proliferation and differentiation of a variety of cells. It modulates the activity of these cells following binding to cell surface receptors. The amino acid sequence of its extracellular domain defined it as a member of the hematopoietin receptor superfamily.
Polymorphisms are associated with resistance to atopy and progression of AIDS symptomatology.
Khurana Hershey et al. () described a polymorphism of the IL4A gene that occurred with increased frequency in patients with allergic inflammatory disorders. The variant allele consisted of an A-to-G transition at nucleotide 1902, causing a change from glutamine to arginine at codon 576 (Q576R) in the cytoplasmic domain of the interleukin-4 receptor alpha protein. The R576 allele was found in 3 of 3 patients with the hyper-IgE syndrome and in 4 of 7 patients with severe atopic dermatitis. Among 50 prospectively recruited adults, it was found in 13 of 20 subjects with atopy and in 5 of 30 without atopy; the relative risk of atopy among those with a mutant allele was 9.3. The R576 allele was associated with higher levels of expression of CD23 by interleukin-4 than was the wildtype allele. This enhanced signaling was associated with a change in the binding specificity of the adjacent tyrosine residue at position 575 to signal-transducing molecules.
Soriano et al. (2005) determined that the V50 allele predominated in HIV-positive long-term nonprogressors (LTNPs), whereas the I50 allele predominated in healthy controls, typical progressors, and those at risk for infection due to sexual exposure or treatment of hemophilia. Homozygosity for V50 was increased in LTNPs compared with other groups. Soriano et al. () concluded that V50 homozygosity appears to be associated with slow progression to AIDS after HIV infection.