A rapid, inexpensive and disposable point‐of‐care blood test for sickle cell disease using novel, highly specific monoclonal antibodies

Abstract

Summary Sickle cell disease (SCD) is a significant healthcare burden worldwide, but most affected individuals reside in low-resource areas where access to diagnostic testing may be limited. We developed and validated a rapid, inexpensive, disposable diagnostic test, the HemoTypeSC™, based on novel monoclonal antibodies (MAbs) that differentiate normal adult haemoglobin (Hb A), sickle haemoglobin (Hb S) and haemoglobin C (Hb C). In competitive enzyme-linked immunosorbent assays, each MAb bound only its target with <0.1% cross-reactivity. With the HemoTypeSC™ test procedure, the sensitivity for each variant was <5.0 g/l. The accuracy of HemoTypeSC™ was evaluated on 100 whole blood samples from individuals with common relevant haemoglobin phenotypes, including normal (Hb AA, N=20), carrier or trait (Hb AS, N=22; Hb AC, N=20), SCD (Hb SS, N=22; Hb SC, N=13), and Hb C disease (Hb CC, N=3). The correct haemoglobin phenotype was identified in 100% of these samples. The accuracy of the test was not affected by Hb F (0-94.8% of total Hb) or Hb A2 (0-5.6% of total Hb). HemoTypeSC™ requires <1 μl of whole blood and no instruments or power sources. The total time-to-result is <20 min. HemoTypeSC™ may be a practical solution for point-of-care testing for SCD and carrier status in low-resource settings.

Sickle cell anemia in sub-Saharan Africa: advancing the clinical paradigm through partnerships and research

“…The NHLBI Small Business Innovation Research grant program 24 has stimulated development of POC diagnostics for SCA, and several devices have encouraging preliminary results. [25][26][27][28][29] Beyond reported successes and accuracy in controlled laboratory settings, these preliminary findings must be validated in "real world" African settings, to confirm that the devices produce reliable results in the hands of those who will use them. Such efforts are ongoing through partnered research, and we predict that within 3 years, several accurate POC devices will be validated and ready for widespread use across sub-Saharan Africa.…”

A Paper-Based Test for Screening Newborns for Sickle Cell Disease

“…Various modifications of conventional laboratory methods (e.g., lower-cost implementation of IEF20, or a microfluidics-based HE21) as well as novel diagnostic approaches (e.g., density-based separation of sickle RBCs in capillaries2223, or magnetic levitation-based smartphone platforms24) may reduce the cost of testing and/or may be performed at the point-of-care but continue to require highly trained personnel and rely on complex specialized equipment and electricity to operate. Rapid diagnostic tests for SCD based on conventional lateral flow immunoassay technology are instrument- and electricity-free and show great potential252627. However, these tests still require extensive field-testing to determine real-world performance for newborn samples and for tests performed in resource-limited settings, and are subject to well-known limitations of all antibody-based assays, such as limited shelf-lives when ambient temperatures exceed recommended ranges for even short periods of time during shipping, storage or usage – a scenario which is highly likely in resource-limited setting such as sub-Saharan Africa28.…”

Point-of-Care Diagnostics: Recent Developments in a Connected Age

“…One device identified sickle-cell disorders 207 , with an alternate lateral flow test using monoclonal antibodies 208 . Another inexpensive paper-based test enabled controlled transport of red blood cells and measurement of hematocrit 209 .…”