Vitamin B12 transport proteins in patients with HIV-1 infection and AIDS.
BACKGROUND
Low vitamin B12 levels (B12) are often observed in patients infected with human immunodeficiency virus type 1 (HIV-1). The causes underlying this finding are thought to be intestinal malabsorption and/or abnormalities in the vitamin plasma binding proteins (BP).


METHODS
Serum levels of B12 and BP were studied in eighty HIV-1-positive patients, 55 of whom met the diagnostic criteria for AIDS. Subjects were divided into various subgroups: non-AIDS HIV-1 positive versus AIDS; low serum B12 levels (DB12, < 150 pmol/L) versus normal serum B12 levels (NB12); and the results obtained were compared both between groups and with respect to a reference population (RF) of normal volunteers.


RESULTS
Low levels of serum B12 were found in 14 patients (17.5%), without differences between the AIDS and non-AIDS subgroups. The levels of holohaptocorrin (holoHP) were lower in the DB12 group than in the NB12 and RF groups (p < 0.01), and no differences were found between the AIDS and non-AIDS groups. The levels of apotranscobalamin (apoTC) were higher in the AIDS group than in the non-AIDs and RF subjects (p < 0.01), but no differences were found between the DB12 and NB12 groups. Likewise, no differences were noted in the levels of holoTC between the DB12 and NB12 groups. A positive correlation between neutrophil counts and free serum haptocorrin levels (apoHP) (rs = 0.36; p = 0.002), and a negative one between the former and the levels of apoTC (rs = -0.3; p = 0.009) were observed. Furthermore, a positive correlation was detected between the erythrocyte sedimentation rate and the levels of apoHP and TC.


CONCLUSIONS
Low serum levels of HP in HIV-1 positive patients could lead to the low levels of serum vitamin B12 frequently observed in this patient population, while the high levels of TC could merely represent a non-specific marker of inflammation (acute phase, reactant).
Remacha
A F
AF
Department of Hematology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Montagud
M
M
Cadafalch
J
J
Riera
A
A
Martino
R
R
Gimferrer
E
E
D000163:Acquired Immunodeficiency Syndrome / Q000097:blood* / Q000150:complications; D000210:Acute-Phase Reaction; D000328:Adult; D001059:Apoproteins / Q000097:blood*; D005260:Female; D015658:HIV Infections / Q000097:blood*; D015497:HIV-1; D006801:Humans; D015994:Incidence; D007297:Inpatients; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009503:Neutropenia / Q000097:blood / Q000150:complications; D010045:Outpatients; D014155:Transcobalamins / Q000032:analysis* / Q000172:deficiency; D014805:Vitamin B 12 / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000150:complications* / Q000453:epidemiology
D001059:Apoproteins; D014155:Transcobalamins; D014805:Vitamin B 12