الفهرس 
Immune-Mediated Hemolytic AnemiaOnly 14 pages are availabe for public view
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Abstract
IMHA represents the most common type of acquired HA that is mediated by pathological Abs (Igs) directed against Ags on RBC surface, leading to its destruction and consumption with resultant anemia. Spherocytes in a peripheral blood film with a positive DAT, a gold standard test, is also known as ”Coombs’ test”; are characteristic findings.
AIHA represents a fairly uncommon group of disorders that may occur at any age with affection of females more than males. It is defined as a type of acquired HA, in which immune system of the body attacks its own RBCs as if they are foreign. AIHA results when a patient’s immune system produces pathologic Abs attaching to and lead to premature destruction or hemolysis of their RBCs with a consequent anemia.
Diagnosis of AIHA is usually not seriously considered in absence of a positive Coombs’ test. So, Coombs’ negative AIHA is such a diagnostic dilemma for hematologists. More sensitive methods can reveal RBC-bound IgG Abs or complement components in DAT-negative patients such as; IRMA, ELAT, ELISA, FC and GT.
This work was conducted to evaluate the use of both GT and FC techniques for diagnosis of Coombs’ negative AIHA.
This study was carried on 2 groups; patients group and control group. The patient group composed of 25 patients referred to Haematology unit of Ain Shams University hospitals, suspected to have AIHA with Coombs’ negative test. They were 10 males (40 %) and 15 females (60 %) with a male to female ratio 1:1.5. Their ages ranged from (14 to 75 years) with a mean age of 39.2±17.2 years. According to causes of AIHA, patient group was divided into 2 subgroups; 9 (36 %) were primary cases represented in Group A, and 16 (64 %) were secondary to underlying diseases represented in Group B.
Out of the 25 patients, 23 (92 %) patients were positive by GT and only two (8 %) patients were negative. Positive cases were graded according to grades (G) of agglutination reactions into; G1 represented in 3 (12 %) patients, G2 represented in 7 (28 %) patients, G3 and G4 represented in 11 (44 %) patients and 2 (8 %) patients respectively. As for FC assay, all of the 25 patients were positive, with >20% cut off for positive expression. The results were expressed as [Expression %] that ranged from 25.3 to 47% with a mean of 33.49 ±5.51% and [MFI] ranged from 1.04 to 9.6 with a mean of 4.51 ±2.47.
On comparing patient and control groups, there were no statistically significant differences as regards demographic data [P=0.28 (for age) and P=0.09 (for gender)]. However, highly statistically significant differences (P<0.0001) were observed between the two groups in laboratory data, as mean RBCs count, Hb concentration and HCT value being lower in patients.
A statistically significant difference was also found in mean MCH value between patient and control groups (P=0.003). Nevertheless, there was no statistically significant difference as regards mean MCV when both groups were compared (P=0.76). Finally, on comparing FC assay results between both groups, a highly statistically significant difference was observed in mean expression % and MFI, where patients showed significantly higher results than control group (P<0.0001).
There was no association between GT grades of patient group and demographic or laboratory data (P>0.05), as well as no correlations were found between FC assay results and laboratory data of patient group (P>0.05). Additionally, no statistically significant difference was observed between GT grades and FC results of patients [% (P=0.86) & MFI (P=0.89)].
The comparative study between both patient subgroups showed a statistically significant difference (P=0.05) regarding age as Group A patients were significantly younger, however no statistically significant difference was observed regarding sex distribution (P=0.23). As for FC assay and GT results (grades), there were no statistically significant differences between Group A and Group B patients, whereas (P=0.14 & 0.42) for expression % & MFI respectively. Also, (P=0.51) for [G1,2] and (P=0.52) for [G3,4].
The best cut off values for both expression % and MFI were calculated, using ROC curve. These were >17.5% for expression % and =1.74 for MFI.
Accordingly, FC assay in our study represented in; expression % was the highest sensitive test (100%), followed by MFI test (96%). As regards GT, it showed a sensitivity of 92 %.