Serological investigations on penicillin-induced antibodies in the Thai population.

Objectives: The study aimed to assess the conditions for coating RBCs with penicillin and examine the anti-penicillin reactions of random Thai patients' sera against penicillin-coated RBCs and normal sera from Thai donors testing in the presence of the drug.

Background: Penicillin-induced immunologic haemolytic anaemia (IHA) is reportedly related to possessing antipenicillin antibodies, immunoglobulin G (IgG), which has been identified in testing penicillin-coated red blood cells (RBCs). In addition, low titre penicillin antibodies, often IgM, are detected in donors by testing in the presence of a solution of the penicillin.

Materials and methods: Penicillin-coated RBCs were produced, and antipenicillin was tested against those penicillin-coated RBCs amongst random Thai patients who had strongly positive direct antiglobulin (≥3+). Additionally, sera from Thai blood donors were tested in the presence of the penicillin. These relationships were determined by comparing the numbers of penicillin-antibody positive patients with their diagnosis, sex, age and blood type.

Results: Penicillin requires a high pH to optimally adhere to RBCs that showed validated reactions with controls. Enrolment of 304 random patients, of whom 17 (5.59%) had positive antipenicillin tests using penicillin-coated RBCs. Of the 246 donor samples, 3 (1.22%) displayed positive reactivities in the presence of soluble penicillin. Furthermore, no association was discovered between the patient's characteristics and antipenicillin positivity.

Conclusions: This is the first study to develop and report on the low percentage of patients' and donors' sera without IHA. Investigating suspected cases of penicillin-induced IHA requires following our suggested method to identify clinically significant antipenicillin.