A rare case of naturally occurring allo anti-Jk(a) missed in manual screening test on tube method

BACKGROUND: Antibodies to the Kidd blood group are mainly red blood cell (RBC) immune, but a few reports on naturally occurring antibodies have been documented. AIM: The aim of this study is to study the anti-Jk(a) for its unusual reactivity with different serological methods. MATERIALS AND METHODS: Donor's plasma was tested with RBCs from in house donors and commercial panels by manual and automated devices. RESULTS: A 36-year-old male blood donor with naturally occurring anti-Jk(a) is detected by solid-phase assays and the gel card technique but not by the tube method. The IgG antibody with the titer of >32 was not a complement-fixing hemolysin, showed a reduced reactivity with enzyme-treated RBCs, and was detectable through 8 months' follow-up period. The donor was typed as (Jk(a−). CONCLUSION: An unusual naturally occurring anti-Jk(a) detected by solid-phase red-cell adherence but not reacting by tube technique reflected on the sensitivity of the methods used.