We investigated antibodies against pX gene product, p40mx, by ELISA using recombinant p40tax protein in HTLV‐I seropositive carriers as well as patients with adult T cell leukemia (ATL) and HTLV‐I‐associated myelopathy (HAM). Seventy (49.0%) out of 143 HTLV‐I healthy carriers were found to be positive for antibody against p40tax antigen and the follow‐up samples at two‐year intervals revealed constant reactivity by ELISA in each carrier. The onset of antibody production was delayed 4 to 12 weeks as compared with anti‐HTLV‐I in primary infection cases. The anti‐p40tax‐positive rate (90%) in HAM patients was significantly higher than that of healthy carriers, acute and chronic ATL patients and their family members. Furthermore, HAM patients and a few healthy carriers showed high reactivities by ELISA. Children from mothers with anti‐p40tax showed a higher anti‐HTLV‐I‐positive rate than that of children from mothers without anti‐p40tax (54.5% versus 12.5%). Two men without anti‐p40tax and one female with low anti‐p40tax developed ATL during follow‐up studies. These results suggest that HTLV‐I carriers could be divided into 2 or 3 sub‐populations according to antibody response to p40tax. A smaller population with anti‐p40tax, especially a high antibody reactivity, could have a high risk of developing HAM and of transmission from mother to child. In addition, ATL may occur in a population with low or absent anti‐p40tax.

SUMMARY1. The planar phospholipid bilayer technique was used to study the T-tubule skeletal muscle dihydropyridine (DHP)-sensitive calcium (Ca2") channel. To improve the signal-to-noise ratio, Ca2" channel activity was recorded using both 800-50 and 500-50 mm NaCl gradients.2. Ca21 channels were characterized by their cation selectivity and pharmacological profile. The mean open time for channels identified by these techniques was increased by the DHP agonist Bay K 8644 (2 /LM), while it was decreased by the DHP antagonist nifedipine (5 /yM). Nifedipine also reduced Ca21 channel amplitude levels.3. Immunoglobulins G (IgG) from three amyotrophic lateral sclerosis (ALS) patients (n = 14 experiments), one myasthenia gravis (MG) patient (n = 3 experiments) and one healthy individual (n = 4 experiments), were tested on Ca21 channel activity at a final concentration of 3 mg/ml. 4. Channel mrean open time, mean closed time and time integral for the current were not modified by normal IgG (n = 4 experiments). Similarly, MG IgG did not reduce channel activity (n = 3 experiments).5. ALS IgG reduced the mean open time of DHP-sensitive Ca21 channel activity in twelve out of fourteen experiments. In addition, in five out of twelve experiments, ALS IgG stabilized the channel to a smaller amplitude level.6. ALS IgG reduced Ca21 channel activity in a side-selective fashion, probably corresponding to the external side of the channel.7. These results suggest that ALS IgG action on DHP-sensitive Ca2+ channels is not mediated by second messengers, thus favouring a direct mechanism for interaction with the DHP receptor complex.

The abnormal lymphocytes in adult T cell leukemia (ATL) reveal a peculiar morphology that is characterized by indented or lobulated nuclei. While human T lymphotropic virus type I (HTLV-I) is thought to be integrated in ATL cells, the correlation between the nuclear irregularities and HTLV-I infection is obscure. We have devised a novel single cell polymerase chain reaction (PCR) technique to examine the integration of HTLV-I provirus genome in cells from two patients with ATL. To isolate single cells, peripheral blood smears were prepared on thin polyester slides and stained with May-Grü nwald-Giemsa. Morphologically defined single cells were cut out after light microscopy. The HTLV-I DNA sequences were detected not only in ATL cells but also in normal-looking lymphocytes. This novel PCR method may provide a valuable tool for understanding the molecular events associated with HTLV-I infection at the single cell level.

Amyotrophic lateral sclerosis (ALS) is a human disease involving upper and lower motoneurons. In this paper we studied the action of specific antigen-binding site (Fab) fragments of immunoglobulins from ALS patients on dihydropyridine (DHP)-sensitive Ca2+ channel function in situ. Ca2+ channels in single mammalian skeletal muscle fibers tested by the double Vaseline gap technique and single Ca2+ channels reconstituted into bilayer were tested in these experiments. Although the observed current-voltage relationship was not modified by the addition of Fab fragments (1.5 mg/ml), peak Ca2+ current (ICa) was significantly reduced. The effect of these Fab fragments on the peak ICa reached a stable value after 60 min of incubation. ALS Fab fragments also slowed the ICa rising phase and increased the rate of tail current deactivation. Studies with double pulses demonstrated that ICa inactivation time course, voltage dependence, and recovery were not modified by ALS Fab fragments. Fab fragments from normal subjects and heat-inactivated Fab fragments from ALS patients did not induce any modification on the charge movement and ICa. In single channel studies, ALS Fab fragments reduced channels amplitude. These data support the concept of an immunological interaction between the circulating antibodies from ALS patients and DHP-sensitive Ca2+ channels.

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