Ramifications of the HLA-I Allelic Reactivity of Anti-HLA-E*01:01 and Anti-HLA-E*01:03 Heavy Chain Monoclonal Antibodies in Comparison with Anti-HLA-I IgG Reactivity in Non-Alloimmunized Males, Melanoma-Vaccine Recipients, and End-Stage Renal Disease Patients

Mepur H Ravindranath; Narendranath M Ravindranath; Fatiha El Hilali; Senthamil R Selvan; Edward J Filippone

doi:10.3390/antib11010018

Ramifications of the HLA-I Allelic Reactivity of Anti-HLA-E01:01 and Anti-HLA-E01:03 Heavy Chain Monoclonal Antibodies in Comparison with Anti-HLA-I IgG Reactivity in Non-Alloimmunized Males, Melanoma-Vaccine Recipients, and End-Stage Renal Disease Patients

Antibodies (Basel). 2022 Mar 2;11(1):18. doi: 10.3390/antib11010018.

Authors

Mepur H Ravindranath^{1

2}, Narendranath M Ravindranath³, Fatiha El Hilali⁴, Senthamil R Selvan⁵, Edward J Filippone⁶

Affiliations

¹ Department of Hematology and Oncology, Children's Hospital, Los Angeles, CA 90027, USA.
² Emeritus Research Scientist at Terasaki Foundation Laboratory, Santa Monica, CA 90064, USA.
³ Norris Dental Science Center, Herman Vostro School of Dentistry, University of Southern California, Los Angeles, CA 90089, USA.
⁴ Faculty of Medicine and Pharmacy of Laayoune, Ibn Zohr University, Agadir 70000, Morocco.
⁵ Tetracore Inc., Rockville, MD 20850, USA.
⁶ Division of Nephrology, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19145, USA.

Abstract

Serum anti-HLA-I IgG are present in non-alloimmunized males, cancer patients, and transplant recipients. Anti-HLA-I antibodies are also present in intravenous immunoglobulin (IVIg), prepared from the plasma of thousands of healthy donors. However, the HLA-Ia reactivity of IVIg diminishes markedly after passing through HLA-E HC-affinity columns, suggesting that the HLA-I reactivity is due to antibodies formed against HLA-E. Hence, we examined whether anti-HLA-E antibodies can react to HLA-I alleles. Monoclonal IgG antibodies (mAbs) against HCs of two HLA-E alleles were generated in Balb/C mice. The antibodies were analyzed using multiplex bead assays on a Luminex platform for HLA-I reactivity. Beads coated with an array of HLA heterodimers admixed with HCs (LABScreen) were used to examine the binding of IgG to different HLA-Ia (31-HLA-A, 50-HLA-B, and 16-HLA-C) and Ib (2-HLA-E, one each of HLA-F and HLA-G) alleles. A striking diversity in the HLA-Ia and/or HLA-Ib reactivity of mAbs was observed. The number of the mAbs reactive to (1) only HLA-E (n = 25); (2) all HLA-Ib isomers (n = 8); (3) HLA-E and HLA-B (n = 5); (4) HLA-E, HLA-B, and HLA-C (n = 30); (5) HLA-E, HLA-A*1101, HLA-B, and HLA-C (n = 83); (6) HLA-E, HLA-A, HLA-B, and HLA-C (n = 54); and (7) HLA-Ib and HLA-Ia (n = 8), in addition to four other minor groups. Monospecificity and polyreactivity were corroborated by HLA-E monospecific and HLA-I shared sequences. The diverse HLA-I reactivity of the mAbs are compared with the pattern of HLA-I reactivity of serum-IgG in non-alloimmunized males, cancer patients, and ESKD patients. The findings unravel the diagnostic potential of the HLA-E monospecific-mAbs and immunomodulatory potentials of IVIg highly mimicking HLA-I polyreactive-mAbs.

Keywords: HLA-E; HLA-Ia; HLA-Ib; closed conformers; heavy chain; heterodimers; luminex; mean fluorescent intensity (MFI); monoclonal IgG antibodies; monomeric; monospecific; multiplex bead assays; open conformers; polyreactive; α1 and α2 helices; β2microglobulin.