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Case Study O1 - Discussion Part 4a - Passive antibodies
 

TraQ Program of the BC PBCO

Monday, 25 September 2017

Case Study O1 - Discussion Part 4a - Passive antibodies

According to the manufacturer, besides anti-D, WinRho SDF TM contains trace amounts of anti-C, -E, -A and -B.9

However, Rushin et al.13 found additional passively acquired alloantibodies in patients treated with RhIG for ITP and in production lots of the product, likely because they tested for the presence of antibodies by an antiglobulin method using a particularly sensitive method (solid-phase RBC adherence assay [Capture-R Ready Screen, Immucor, Norcross, GA]).

  • In production lots, besides Rh system antibodies (anti-D, -C, -E, -G, -V), anti-Fya and -Jka were found in the 4 lots tested

  • Anti-Jkb and -S were present in one lot each

  • Anti-D titers ranged from 32,000 to 128,000. Titers of other antibodies varied by specificity (Table 3).

Table 3. Titers of antibodies in 4 lots of IV RhIG13

Anti-

C

E

G

V

Fya

Jka

Jkb

S

Titer
range

128-2048

2-16

128-1048

8-32*

2-8

4-8

8+

8+

*3 lots; +one lot only

All 16 patients with ITP who received IV RhIG developed both a positive DAT (3+ to 4+) and a positive antibody screen result.13 An initial dose of 50 µg/kg (250 IU/kg) had been given to patients and, if required, a subsequent dose of 25 to 60 µg/kg (125?300 IU/kg).

Depending on the patient?s phenotype:

  • Plasma and red cell eluates commonly contained combinations of anti-D, -G, -C, and -E.

  • Eluates also contained anti- Fya (2 patients) and anti-Jka, -Jkb , and -V (1 patient each).

  • Anti- Fya was found in one patient?s plasma, as was anti-V.

In a published review of 15 cases of severe hemolysis following IV RhIG therapy for ITP reported to the FDA,12 only limited serologic data were available.

  • Elutions from the red cells of three patients with DAT results positive for IgG and negative for complement revealed only anti-D.
  • Antibody screen results (available for three patients) were negative for two and positive for anti-C in a known C-negative patient.

TraQ self study question

1. RhIG has been shown to contain many antibodies. Since the product is anti-D immune globulin, how does this happen?

Answer

More Discussion...

Last modified on Thursday, 18 May 2017 07:32