How it identify Anti-Cw

[kirkaw]

We recieved a specimen on an Rh negative patient who had recieved RhIg. Her antibody screen was positive, but did not match a pattern for anti-D. A panel was run. The cell yielding the stronest reaction was Cw positive. Everything else was ruled out except the (passive) anti-D. I could not find a Cw positive, D- cell on any panel. I could not find references in the Technical Manual to the prevalence of the Cw antigen being present on D- cells. Is Cw always on D+ cells? Thanks.

[JEMarti]

Like Big C, Cw will be found on D positive patients most frequently. Your best bet may be to indicate that you cannot rule out Cw (or report it as a possible Cw) and get a redraw in several months once she no longer has the RhIg in her system.

[Malcolm Needs ☆]

We recieved a specimen on an Rh negative patient who had recieved RhIg. Her antibody screen was positive, but did not match a pattern for anti-D. A panel was run. The cell yielding the stronest reaction was Cw positive. Everything else was ruled out except the (passive) anti-D. I antigen always found could not find a Cw positive, D- cell on any panel. I could not find references in the Technical Manual to the prevalence of the Cw antigen being present on D- cells. Is Cw always on D+ cells? Thanks.

By no means is the Cw antigen confined to D+ red cells and, contrary to what an awful lot of people think, nor is the Cw antigen confined to C+ red cells. T cells (and the Cw antigen is antithetical to MAR and Cx, but not to C or c).

In a situation like this, you could adosrb out the anti-D using R2R2 red cells, and then test the adsorbed plasma against R1wR1 (and R1R1 cells, as a negative control).

rr red cells that are Cw+ are incredibly rare, but, as the patient has already made anti-D and, possibly, anti-Cw, it would always be worthwhile cross-matching by IAT, rather than by immediate spin.

I will attach a little article I wrote with my colleague Alan Gray a few years ago for the BBTS, but this article is actually available in the Library section of this website.

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[Mabel Adams]

You have no worries if transfusion is the issue; just AHG xm Rh neg blood. If you need to determine the risk of HDFN from anti-Cw you may never get past the passive anti-D since she may get another dose at 28 wks--assuming the patient is currently in the first or second trimester of pregnancy and not receiving RhIG for some other reason.