PARABEN-DEPENDENT ANTI-Rh Volume 41, March 2001 TRANSFUSION 371 www.transfusion.org E sters of p-hydroxybenzoic acid (parabens) are added to a commercially available LISS(C-LISS) to retard microbial growth. We have described ex amples of anti-Jk a that react only when parabens or related compounds are present in the reaction mixture. 1 Because active compounds had to be present in mixtures of serum plus RBCs for serologic reactivity to occur, Halima et al. 2 suggested that these examples of anti-Jk a react by an immune complex mechanism. In this report, we describe the first example of a paraben-dependent antibody to an Rh protein that does not require the presence of paraben in the reaction milieu. Rather, this antibody appears to re- act with a neoantigen formed between propylparaben or re- lated compounds and an Rh protein. CASE REPORT The patient is a 24-year-old untransfused woman who re- cently moved to the United States from Yemen. She was seen at the University of Michigan Health Systems (UMHS) for evaluation of primary infertility; she was treated with oral clomiphene citrate and Provera, and she subsequently conceived. This is the patient’s first known pregnancy. We received blood samples for routine prenatal testing: ABO and Rh typing and tests for unexpected antibodies. Her blood typed as group A, R 1 r (D+C+c+E–e+), and indirect antiglobulin tests (anti-IgG) for unexpected anti- bodies by using R 1 R 1 and R 2 R 2 RBCs stored in C-LISS were The first example of a paraben-dependent antibody to an Rh protein W. John Judd, Jill R. Storry, Thomas D. Annesley, Marion E. Reid, Michelle Bensette, Sherry Waddington, LouAnn Dake, David Rohrkemper, and Ricardo Valdez BACKGROUND: Parabens are added to a commercial LISS (C-LISS) to retard microbial growth. Paraben- dependent anti-Jk a has been detected by the use of C-LISS. CASE REPORT: Serum from a D+ woman reacted in antiglobulin tests with RBCs stored (2-4 hours, 22-25°C) in C-LISS (Löw and Messeter formulation, Immucor). Freshly prepared C-LISS-suspended RBCs did not re- act; nor did RBCs stored in LISS-additive reagents, PEG, saline, or homemade LISS. RESULTS: Studies using C-LISS-stored RBCs revealed an antibody that reacted with D+ and rrV+ RBCs, but not with r´r, r´´r, or rrV–VS– RBCs. All partial D RBC pheno- types tested reacted, as did D+LW–, r G r, r´´ G r, r y r, r´ s rV+VS+, and r´ s rV–VS+ RBCs. The active ingredient in C-LISS was propylparaben. Other LISS ingredients were not required; saline solutions of propylparaben, ethylparaben, methyl salicylate, 2-phenoxyethanol, and butylparaben were active. Methylparaben and methyl-m- hydroxybenzoate were inactive. Reactivity to C-LISS- stored RBCs could not be inhibited by propylparaben. Reactivity with D+V– and D–V+VS+ RBCs was not separable by adsorption-elution. CONCLUSIONS: This antibody likely detects a neoantigen formed between active compounds and RBC membranes. Review of the structure of active com- pounds suggests that proximity between methyl and hy- droxyl groups is important for binding with RBC mem- branes. The role of RhD is unclear; no single portion of RhD protein appears to be implicated. ABBREVIATIONS: C-LISS = commercial LISS; UMHS = Univer- sity of Michigan Health Systems. From the Department of Pathology, University of Michigan, Ann Arbor, Michigan; and the New York Blood Center, New York, New York. Address reprint requests to: W. John Judd, FIBMS, MIBiol, Department of Pathology, UH-2G332, University of Michigan Hospitals, 1500 East Medical Center Drive, Ann Arbor, MI 48109- 0054; e-mail: johnjudd@umich.edu. Received for publication June 19, 2000; revision received September 11, 2000, and accepted September 14, 2000. TRANSFUSION 2001;41:371-4. I M M U N O H E M A T O L O G Y