"Cross reactivity" refers to when a substance or material triggers a response in the body that is meant for a different substance. It occurs when the body mistakes a similar substance for a different one and reacts in a similar way. Full definition
These preliminary results indicate that the recombinant scFv form of the mAb 5.91 will be more effective at blocking IgE binding to cell surface receptors as well as decreasing the potential of cross reactivity of the lymphocyte cell population with the IgG Fc receptors than the original mAb 5.91. (oldenglishsheepdogclubofamerica.org)
50 % of people with gluten sensitivities also experience cross reactivity with other foods, including casein in milk products, corn, coffee, and almost all grains, because their protein structures are similar. (everywomanover29.com)
Geographic distribution of D. immitis and D. repens coincides (Fig. 5) in many areas of South Europe (Genchi et al., 1995; Rossi et al., 1996) and cross reactivity between the two nematodes is regularly shown by different tests, producing false seropositive results (Schrey, 1996). (priory.com)