Letter to the Editor: HUMAN PARVOVIRUS B19 ASSOCIATED WITH IDIOPATHIC THROMBOCYTOPENIC PURPURA

I have read the interesting report by Dr. Atkepe et al. related to human parvovirus B19 (PVB19) associated with idiopathic thrombocytopenic purpura (ITP) in 19 patients [[1]]. They found parvovirus B19-specific IgM and IgG antibodies 57 and 73% of the patients, but viral genome was detected in the sera of only 9 (47%) of the 19 patients.

We also studied PVB19-specific IgM and IgG antibodies, by ELISA in 35 patients newly diagnosed with acute ITP, aged 4 months to 15 years (18 males and 17 females). No history of exposure to toxins and chemicals or of recent immunization could be obtained in the patients. We could not find PVB19-specific IgM positivity in our patients, and the IgG positivity was only 17% in the patients (Table 1). But we could not study viral genome by PCR in any of them (unpublished data).

TABLE 1 Some Characteristics of PVB19 IgG-Positive Patients

Patient	Age (years)	Sex	Platelel count	IgM	G
M.E.	10	F	1,000	–	+
T.M.	11/12	F	2,000	–	+
N.K.	4	F	12,000	–	+
M.Z.C.	3.5	M	2,000	–	+
M.E.U.	4	M	2,000	–	+
F.E.	6.5	M	1,000	–	+

We published a paper on the incidence of parvovirus B19 seropositivity among thalassemia major patients and a control group from Ankara, Turkey, in this journal [[2]]. Although the number of thalassemic individuals was small, there existed a discrepancy between thalassemics and controls: 22 of 54 (41%) versus 122 of 177 (68%) (p < 0.005) (Table 2). It is well known that HPV-B19 shows tropism to blood group P antigen [[3]]. When the P blood group phenotype in our thalassemic patients and control group was combined, P blood group phenotype prevalence in patients with β-thalassemia major was lower than that of the control group (p <. 01) (Table 2) [[4]].

TABLE 2 Erythrocyte P Antigen and PVB19 Seropositivity in β-Thalassemia Major Patients and Control Group

Groups	P antigen (%)	IgM (%)	IgG (%)
Thalassemic	59.6	7	41
Control	80.3	0	68

The PVB19-specific IgG positivity in our patients with acute ITP was lower than the value of Aktepe et al. If we had studied P blood group type in our patients, we could have explained the results in more detail. The number of our patients here is very limited also. Therefore, further analysis should lead to a better understanding of its tropism and pathophysiology.